bluuebunny/crossref_metadata_2025 huggingface dataset:
Hamstrings—an anterior cruciate ligament protagonist
Authors: More Robert C. , Karras Bryant T. , Neiman Rafael , Fritschy Daniel , Woo Savio L-Y , Daniel Dale M.
Published: June 2007

A cadaveric model that incorporated quadriceps and hamstrings muscle loads was developed to simulate the squat exercise. The addition of hamstrings load affected knee kinematics in two ways. First, anterior tibial translation during flexion ("femoral roll-back") was significantly reduced ( P = 0.003) and second, internal tibial rotation during flexion was reduced ( P = 0.008). However, quadriceps force was unaffected by the ad dition of hamstrings load. Thus, it seems likely that hamstrings muscle activity that has been observed in vivo during a squat probably functions synergistically with the anterior cruciate ligament to provide anterior knee stability.

After the ACL was sectioned, anterior tibial transla tion was significantly increased during the squat ( P = 0.04). The anterior cruciate ligament was then recon structed using a graft instrumented with a load cell. During passive motion, maximal graft tension was at full extension. During simulated squat exercise, the addition of hamstrings caused a significant decrease in graft load ( P = 0.006). During the squat, maximal graft tension was at full extension, and was equal to the graft tension at full passive extension. Thus, the squat exercise may be useful in the early stages of anterior cruciate ligament rehabilitation.
The effect of rehabilitation and return to activity on anterior-posterior knee displacements after anterior cruciate ligament reconstruction
Authors: Barber-Westin Sue D. , Noyes Frank R.
Published: June 2007

Anterior-posterior knee displacements were measured sequentially with the KT-1000 arthrometer on 84 pa tients after anterior cruciate ligament reconstruction for chronic deficiency. We determined the correlations be tween the initial onset of abnormal displacements (greater than 2.5 mm between limbs) and time from surgery or the phase of rehabilitation.

Group 1 ( N = 52) had a bone-patellar tendon-bone allograft and Group 2 ( N = 32), an iliotibial band extraar ticular procedure in addition to the allograft. The mean followup was 37 months (range, 23 to 65).

At followup in Group 1, 24 patients (46%) had less than 3 mm of displacement between limbs, 22 (42%) had 3 to 5.5 mm, and 6 (12%) had greater than 5.5 mm. In Group 2, 23 patients (72%) had less than 3 mm of displacement, 8 (25%) had 3 to 5.5 mm, and 1 (3%) had greater than 5.5 mm. The difference between the groups was significant ( P < 0.05).

The advanced rehabilitation program of immediate knee motion and early weightbearing, did not result in an increased incidence of abnormal displacements in the early phases. The abnormal displacements typically occurred during the latter two rehabilitation phases (intensive strength training or return to sports). Further, one-third of the abonormal displacement occurred more than 2 years postoperatively.
Effect of surgical timing on recovery and associated injuries after anterior cruciate ligament reconstruction
Authors: Wasilewski Stephen A. , Covall David J. , Cohen Sharon
Published: June 2007

This study was undertaken to determine the optimal time after injury for arthroscopically assisted anterior cruciate ligament reconstruction using a double semi tendinosus graft. We analyzed 87 patients. Time from injury to surgery was established as acute, subacute, or chronic; the three groups were matched. Meniscal damage and treatment were categorized. Chondral le sions were graded, postoperative parameters of mo tion, strength recovery, and stability were tabulated at 3, 6, 12, and 18 months. Complications were com pared.

Six percent of the patients with chronic knee injuries had two normal menisci at surgery, compared with 29% of the acute and subacute groups. Reparable tears were found in 37.8% of the knees. Chondral lesions were found in the tibiofemoral joint in 17% of acute, 7% of subacute, and 44% of the chronic knees. Postoperative motion recovery was significantly less at all time intervals for the acute group. Quadriceps strength recovery was slower in the acute knees. Sta bility was similar in all groups. Arthrofibrosis was found in 22% of acute, 0 subacute, and 12.5% of the chronic knees. Patellofemoral pain was noted in 17% of the acute, 0 of the subacute, and 9.3% of the chronic knees.

This study showed that surgery done within 6 months of injury does not jeopardize the knee. Recovery after acute anterior cruciate ligament reconstruction is sig nificantly slower than after subacute or chronic recon struction.
Longitudinal rupture of the peroneal tendons
Authors: Bassett Frank H. , Speer Kevin P.
Published: June 2007

To determine more precisely the injury mechanism of the peroneal tendon longitudinal tear, we studied 15 cadaveric lower extremities. Our study was motivated by our observation from a retrospective study of ath letes treated by one surgeon (FHB) over a 17-year period. Eight patients who sustained lateral ankle sprains by plantar flexion and inversion of the foot on the leg also had longitudinal tears (1 to 3 cm) of the peroneal tendon—five in the peroneus longus and three in the peroneus brevis. All of the lateral ankle sprains were successfully managed nonoperatively. However, even after a period of rehabilitation, when their ankles should have been asymptomatic, the patients continued to complain of persistent lateral ankle swelling, popping, and retrofibular pain. On physical examination, all ankles were clinically stable. Palpable retrofibular pop ping occurred with active foot rotation. There was no evidence of peroneal tendon instability. Radiographs were normal and tenograms were suggestive of pero neal tendon injury but did not have the specificity to reveal the rupture. Primary suture repair of this peroneal tendon split was performed and gave excellent long- term results. The cadaveric studies revealed that the tear of the tendon could occur in the 25° to 15° range of plantar flexion as the peroneus longus impinged against the tip of the fibula and as the peroneus brevis impinged against the lateral wall of the peroneal groove or against the longus tendon.
Surgical treatment of Freiberg's infraction in athletes
Authors: Sproul Jack , Klaaren Hobart , Mannarino Frank
Published: June 2007

Ten patients with 11 cases of Freiberg's infraction were studied retrospectively. The patients had varying amounts of sports participation. All cases were treated surgically, most after some form of nonoperative inter vention. Surgery consisted of metatarsophalangeal joint debridement, except in 1 patient where the meta tarsal head was resected. All patients had improvement of their symptoms and 80% of normal joint range of motion was restored. No patient had joint space nar rowing or major arthritic changes on follow-up roent genographic studies.
Biomechanical considerations in patellofemoral joint rehabilitation
Authors: Steinkamp Lisa A. , Dillingham Michael F. , Markel Mark D. , Hill Jennifer A. , Kaufman Kenton R.
Published: June 2007

Patellofemoral joint biomechanics during leg press and leg extension exercises were compared in 20 normal subjects (10 men, 10 women) aged 18 to 45 years. Knee moment, patellofemoral joint reaction force, and patellofemoral joint stress were calculated for each subject at four knee flexion angles (0°, 30°, 60°, and 90°) during leg press and leg extension exercises.

All three parameters (knee moment, patellofemoral joint reaction force, and patellofemoral joint stress) were significantly greater in leg extension exercise than leg press exercise at 0° and 30° of knee flexion (P < 0.001). At 60° and 90° of knee flexion, all three param eters were significantly greater in leg press exercise than leg extension exercise (P < 0.001). Patellofemoral joint stresses for leg press and leg extension exercises intersected at 48° of knee flexion.

This study demonstrates that patients with patello femoral joint arthritis may tolerate rehabilitation with leg press exercise better than with leg extension exercise in functional ranges of motion because of lower patel lofemoral joint stresses.
Postoperative pain after anterior cruciate ligament reconstruction using a transligamentous approach
Authors: Solheim Eirik , Strand Torbjørn
Published: June 2007

Anterior cruciate ligament reconstruction by free patel lar tendon graft was performed using 2 different surgical approaches to the intercondylar notch in 67 consecu tive patients with chronic anterior cruciate ligament insufficiency. In the first 30 patients (Group A), the traditional medial parapatellar arthrotomy with lateral luxation of the patella was done, whereas in the last 37 patients (Group B) a transpatellar tendon approach was used. Postoperative pain was managed by analgesics and, in patients who had epidural anesthesia, by ad ministration of bupivacaine in indwelling catheters. Gen erally, the analgesics and bupivacaine were given im mediately on request to establish comfort at rest and to permit range of motion exercises without severe pain. Compared with those in Group A, the patients of Group B had a significantly longer period from the first dose of analgesic or bupivacaine to the second, and the total number of doses of analgesic or bupivacaine was significantly lower. In the subgroup of patients with epidural anesthesia (21 in Group A and 32 in Group B), the Group B patients required significantly less anal gesics, as doses equivalent to 10 mg of morphine, compared with that of Group A.
Prospective study of osseous, articular, and meniscal lesions in recent anterior cruciate ligament tears by magnetic resonance imaging and arthroscopy
Authors: Spindler Kurt P. , Schils Jean P. , Bergfeld John A. , Andrish Jack T. , Weiker Garron G. , Anderson Thomas E. , Piraino David W. , Richmond Bradford J. , Medendorp Sharon V.
Published: June 2007

Fifty-four patients with anterior cruciate ligament tears that were arthroscopically reconstructed within 3 months of initial injury were prospectively evaluated. Patients with grade 3 medial collateral ligament, lateral collateral ligament, or posterior cruciate ligament tears were excluded. Eighty percent of our patients had a bone bruise present on the magnetic resonance image, with 68% in the lateral femoral condyle. Two of the latter findings—an abnormal articular cartilage signal (P = 0.02) and a thin and impacted subchondral bone (P = 0.03)—had a significant relationship with injury to the overlying articular cartilage. Meniscal tears were found in 56% of the lateral menisci and 37% of the medial menisci. A significant association was present between bone bruising on the lateral femoral condyle and the lateral tibial plateau (P = 0.02).

Results of our study support the concept that the common mechanism of injury to the anterior cruciate ligament involves severe anterior subluxation with im paction of the posterior tibia on the anterior femur. Determination of the significance of bone bruising, ar ticular cartilage injury, or meniscal tears will require a long-term followup that includes evaluation for arthritis, stability, and function. These 54 patients represent the first cohort evaluated in this ongoing prospective clinical study.
Arthroscopic treatment of symptomatic extension block complicating anterior cruciate ligament reconstruction
Authors: Fisher Steven E. , Shelbourne K. Donald
Published: June 2007

Arthrofibrosis resulting in loss of knee extension com promises the results of anterior cruciate ligament re constructions. We designed a study to clarify the symp toms and to evaluate the results of arthroscopic treat ment of this complication. Forty-two patients in a series of 959 consecutive open anterior cruciate ligament reconstructions required further surgical treatment for relief of symptoms related to loss of extension. Arthro scopic examination of these knees confirmed the pres ence of an extension block caused by hypertrophy of the ligament or abundant tissue formation in the anterior tibiofemoral joint an average of 9 months after anterior cruciate ligament reconstruction. The offending tissues were excised arthroscopically and the patients were followed with an aggressive rehabilitation program. Thirty-five patients were available for followup an av erage of 28 months after excision of the tissue. Subjec tive functional status and symptomatic status were scored numerically using identical, patient-completed questionnaires before and after the excision procedure. Range of motion, Cybex, and KT-1000 arthrometer results were also recorded. The results were statisti cally compared with results from a control group de mographically matched and selected at random from the 959 patients. Before excision of the offending tis sue, the knee scores of the study group differed signif icantly from those of the control group. However, after the excision procedure, the knee scores of the 2 groups were nearly identical. Marked improvements in function and symptoms (most notably, activity-related anterior knee pain, crepitus at terminal extension, and knee stiffness) were noted in all patients in the study group after removal of the extension block and resumption of an accelerated rehabilitation program. The evidence from this study indicates that an intraarticular block to full knee extension is associated with definite symp toms and disability. When this problem fails to respond to nonoperative treatment, significant improvement can be obtained by arthroscopic excision of the impinging tissue followed by an aggressive rehabilitation program.
Effect of anterior cruciate ligament graft tensioning direction, magnitude, and flexion angle on knee biomechanics
Authors: Gertel Theodore H. , Lew William D. , Lewis Jack L. , Stewart Nathaniel J. , Hunter Robert E.
Published: June 2007

The objective of this study was to determine the bio mechanical effect of graft tensioning during reconstruc tion of the anterior cruciate ligament. We evaluated the magnitude of the tensioning force (22 or 67 N), the flexion angle at which the tension was applied (exten sion or 30° of flexion), and the direction of application of the tensioning force (proximal, distal, or distal with a posterior force simultaneously applied to the tibia) on 10 fresh cadaveric knees. The anterior cruciate liga ment was reconstructed using a bone-patellar tendon- bone graft. The graft was then temporarily fixed during the application of each of 12 combinations of tensioning variables listed above. After each fixation, graft force and joint motion were measured during anterior tibial loads.

Tensioning direction and the flexion angle significantly affected graft force and joint motion, while the magni tude of the graft tensioning did not. Graft forces were greater when the tensioning was applied at 30° of flexion. Compared with distal tensioning with and with out posterior tibial force, graft forces with proximal tensioning were greater in extension and lower in flex ion. The position of the tibia relative to the femur was posterior and externally rotated, compared with normal, for all combinations of tensioning variables in both unloaded and anterior load states.
Overuse ballet injury of the base of the second metatarsal
Authors: Harrington Timothy , Crichton Kenneth John , Anderson Ian F.
Published: June 2007

Performing classical ballet may cause major stress to the feet of the dancer. A variety of foot injuries have been described, with one such injury being an overuse syndrome involving the base of the second metatarsal and adjacent Lisfranc's joint. The diagnosis for this syndrome usually requires differentiating synovitis of Lisfranc's joint from a stress reaction of the base of the second metatarsal. Prompt diagnosis is important since the treatment for these two conditions differs signifi cantly and, in the case of bone stress reaction, delay can cause progression of the lesion. We report good clinical results in a group of eight ballerinas for whom we obtained early diagnosis and treatment of their injuries. This is in contrast to poor results reported in the literature if the diagnosis and management of these types of injuries are delayed. We developed a simple diagnostic protocol to enable diagnosis at presentation. When a bone stress reaction had progressed to a fracture line, a characteristic appearance was found on magnetic resonance imaging, suggesting a specific mechanism of injury. A possible mechanism for this injury is discussed.
Long-term followup of the modified Bristow procedure
Authors: Banas Michael P. , Dalldorf Peter G. , Sebastianelli Wayne J. , DeHaven Kenneth E.
Published: June 2007

A total of 86 modified Bristow procedures were per formed for anterior shoulder instability between 1975 and 1987. Followup on 79 shoulders (92%) was ob tained at an average postoperative time of 8.6 years. The redislocation rate was 4%. Average motion loss was 5° of internal rotation and 9° of external rotation. Fifteen percent of the patients examined expressed mild apprehension with the shoulder abducted and externally rotated. Radiographic bone union of the coracoid transplant was noted in 82% of patients. Additional surgical procedures were required in 14% of patients. Seventy-three percent of the reoperations were for screw removal because of persistent shoulder pain. The average subjective shoulder function was rated at 86% of preinjury level. All throwing athletes were able to return to throwing, although 54% of the patients with dominant shoulder involvement noted a decrease in throwing velocity. Ninety-seven percent of the patients rated their results as good or excellent.
Intraarticular anterior cruciate ligament reconstruction in the symptomatic arthritic knee
Authors: Shelbourne K. Donald , Wilckens John H.
Published: June 2007

We reviewed a consecutive series of young sympto matic patients with chronic anterior cruciate ligament- deficient knees to determine if an autogenous patellar tendon graft reconstruction decreased their symptoms and increased the stability of the knee. All patients had radiographic evidence of posttraumatic arthritis. Thirty- three patients met our criteria for inclusion in the study. Time from injury to reconstruction of the anterior cru ciate ligament averaged 105 months. All patients under went an accelerated rehabilitation program designed to help them regain full range of motion as soon as pos sible. Preoperative and postoperative range of motion, strength, stability, and subjective evaluations were compared. Followup averaged 44.8 months. Follow-up range of motion was not significantly different from preoperative measurements (P = 0.51). Postoperative stability, as measured by KT-1000 arthrometer maxi mum manual test, averaged 2.7 mm versus 8.4 mm preoperatively (P < 0.001). Isokinetic testing revealed no difference in the quadriceps strength after recon struction (P = 0.99). Patients' subjective scores on a modified Noyes questionnaire improved for pain, sta bility, and activity level, with a total improvement from 55 to 81 points. Although the procedure and rehabili tation were successful in providing stability and de creasing pain, patients were still encouraged to limit high-impact athletic and occupational activity.
Outpatient percutaneous screw fixation of the acute Jones fracture
Authors: Mindrebo Norman , Shelbourne K. Donald , Van Meter Charles D. , Rettig Arthur C.
Published: June 2007

Nine patients (8 men and 1 woman, ranging in age from 17 to 22 years) who sustained a Jones fracture were treated with percutaneous intramedullary screw fixation as outpatients. All of the patients were varsity athletes. Seven were Division I scholarship athletes. Beginning at 7 to 10 days after surgery, all patients were allowed weightbearing as tolerated with a CAM walker. Station ary bicycling, swimming, and Stairmaster were allowed at 2 to 3 weeks. The average return to running was 5.5 weeks (range, 3 to 10). The average return to full competition was 8.5 weeks (range, 7 to 12). No periop erative or postoperative complications occurred. Aver age followup was 2.5 years. All fractures attained clin ical and radiographic union. We believe that outpatient percutaneous intramedullary screw fixation of the acute Jones fracture is a reasonable alternative for those active patients who would have difficulty with a non- weightbearing cast and crutches or who desire an expeditious return to activities. Time restraints are par ticularly critical for in-season or preseason athletes. With the outpatient screw fixation method, our patient population had predictable healing, and they returned to full sports participation within 12 weeks.
Quadriceps strength and functional capacity after anterior cruciate ligament reconstruction
Authors: Lephart Scott M. , Kocher Mininder S. , Harner Christopher D. , Fu Freddie H.
Published: June 2007

Harvesting the central third of the patellar tendon for autograft anterior cruciate ligament reconstruction is thought to compromise quadriceps strength and func tional capacity. We compared objective measurements of quadriceps strength and functional capacity in ath letes after patellar tendon autograft or allograft anterior cruciate ligament reconstruction. We looked at 33 ac tive male patients (mean age, 24.3 years) who had anterior cruciate ligament reconstructions 12 to 24 months earlier using patellar tendon autograft (N = 15) or allograft (N = 18) techniques. All patients under went an intensive rehabilitation program. Quadriceps strength and power were assessed by measuring peak torque at 60 and 240 deg/sec, torque acceleration energy at 240 deg/sec, and the quadriceps index using a Cybex II isokinetic testing device. Functional capacity was evaluated based on the results of 3 specially designed functional performance tests and the hop test. Results revealed no significant difference between au tograft and allograft groups with respect to any of these parameters. These findings indicate that harvesting the central third of the patellar tendon for autograft anterior cruciate ligament reconstruction does not diminish quadriceps strength or functional capacity in highly active patients who have intensive rehabilitation. Thus, the recommendation to avoid patellar tendon autograft anterior cruciate ligament reconstruction to preserve quadriceps strength and functional capacity may be unnecessary.
Quantitative analysis of the measuring capabilities of the KT-1000 knee ligament arthrometer
Authors: Kowalk David L. , Wojtys Edward M. , Disher Jeff , Loubert Peter
Published: June 2007

The KT-1000 arthrometer was evaluated in vitro and in vivo to determine accuracy and quantify effects of potential error sources in clinical application. The KT- 1000 arthrometer in vitro accuracy was evaluated by making 30 measurements of 13 known displacements (range, +15 to -15 mm). The effect of applied force on malalignment measurements was evaluated in vitro by making repeated measurements with force applied 5°, 10°, and 15° from the vertical position. The effect of malpositioning the device along the joint line was eval uated in vivo by making repeated measurements 1 cm proximal and 1 cm distal to the joint line. The KT-1000 arthrometer was accurate in vitro (average error, 0.13 mm; SD, 0.12 mm). The range of measurements in creased when the angle of force application was in creased. Positioning the device 1 cm proximal to the joint line produced larger anterior translation measure ments in vivo than those at the joint line (5.8 versus 5.4 mm), while positioning it 1 cm distal produced smaller measurements (4.4 mm). The KT-1000 arthrometer's accuracy indicates great potential for clinical applica tion, but one must ensure that the displacing force is directed properly and the device is positioned accu rately over the joint line.
Locked bucket-handle meniscal tears in knees with chronic anterior cruciate ligament deficiency
Authors: Shelbourne K. Donald , Johnson Glen E.
Published: June 2007

Because we noticed patients had difficulty regaining full range of motion after surgery for a locked bucket- handle meniscal tear with simultaneous reconstruction for a chronic anterior cruciate ligament tear, we adopted a two-stage procedure for this group of patients. We evaluated the results of a two-stage procedure in the knees of 16 athletes (Group 1) and compared their outcome with the outcome of 16 matched athletes who had been treated with simultaneous repair or removal of the displaced bucket-handle meniscal tear and au togenous patellar tendon anterior cruciate ligament re construction (Group 2). Four patients in Group 2 re quired a second procedure or casting to regain full extension. No patient in Group 1 required a second procedure. One meniscal retear was detected in Group 1. The two-stage procedure also appears to have a number of theoretical advantages: 1) more aggressive use of repair rather than removal of a displaced torn meniscus, 2) prevention of problems in regaining range of motion, 3) allows a second look to judge the success of meniscal repair, and 4) allows time for the patient to prepare for anterior cruciate ligament reconstruction physically, mentally, academically, and socially.
The strength of the central third patellar. tendon graft
Authors: Cooper Daniel E. , Deng Xianghua H. , Burstein Albert L. , Warren Russell F.
Published: June 2007

Thirty-seven bone-patellar tendon-bone composite grafts from the knees of 21 human cadavers were tested to failure. Average donor age was 28 years. The composites were divided into 4 groups: 3 groups with 10 grafts (5 pairs) and 1 group with 7 grafts from 6 donors. In Group 1 we tested 10- versus 15-mm wide grafts that were used without twisting; Group II, 10- mm wide grafts without twisting versus 10-mm wide grafts that were twisted 90°; Group III, 10-mm wide grafts twisted 90° versus 10-mm wide grafts twisted 180°; and Group IV, 10- versus 7-mm wide grafts that were not twisted. The tests were performed using a newly described potting technique and clamp system and a servohydraulic testing machine with an elongation rate of 5 cm/sec.

The results of this study suggest that the central third of the patellar tendon is stronger than previously re ported. The mean ultimate load of a 15-mm bone- patellar tendon-bone composite was 4389 N (±708); of the 10-mm wide composites, 2977 N (±516); and of the 7-mm composites, 2238 N (±316). Twisting the graft 90° increased the strength (P < 0.05). Further twisting to 180° had no significant effect compared with twisting 90°. This study supports the practice of using smaller (10 mm) bone-patellar tendon-bone grafts to avoid the potential complications of patellar fracture and graft impingement in the notch.
Vertebral ring apophysis injury in athletes
Authors: Sward Leif , Hellstrom Mikael , Jacobsson BO , Karlsson L.
Published: June 2007

In a radiologic study of the thoracolumbar spine in 143 athletes aged 14 to 25 years and 30 male nonathletes aged 19 to 25 years, abnormalities of the vertebral ring apophyses were analyzed. Abnormalities affecting the anterior part of the vertebral ring apophysis occurred exclusively in athletes and they were most common in wrestlers and female gymnasts. Different types of ab normalities were found and the type of abnormality was related to the spinal level. We propose that this is related to trauma of various types. Excavation of the anterior part of the vertebra, probably from compres sion forces, was mainly found in the thoracic and tho racolumbar junction of the spine. Persisting or enlarged apophysis, probably caused by avulsion of the anterior part of the vertebral ring apophysis, was only found in the lumbar spine.
An epidemiologic study of sports and weight lifting as possible risk factors for herniated lumbar and cervical discs
Authors: Mundt Diane J. , Kelsey Jennifer L. , Golden Anne L. , Panjabi Manohar M. , Pastides Harris , Berg Anne T. , Sklar Joseph , Hosea Timothy
Published: June 2007

The associations between participation in several spe cific sports, use of free weights, and use of weight lifting equipment and herniated lumbar or cervical inter vertebral discs were examined in a case-control epi demiologic study. Specific sports considered were baseball or softball, golf, bowling, swimming, diving, jogging, aerobics, and racquet sports. Included in the final analysis were 287 patients with lumbar disc her niation and 63 patients with cervical disc herniation, each matched by sex, source of care, and decade of age to 1 control who was free of disc herniation and other conditions of the back or neck. Results indicated that most sports are not associated with an increased risk of herniation, and may be protective. Relative risk estimates for the association between individual sports and lumbar or cervical herniation were generally less than or close to 1.0. There was, however, a weak positive association between bowling and herniation at both the lumbar and cervical regions of the spine. Use of weight lifting equipment was not associated with herniated lumbar or cervical disc, but a possible asso ciation was indicated between use of free weights and risk of cervical herniation (relative risk, 1.87; 95% con fidence interval, 0.74 to 4.74).
Pull-out strength of suture anchors for rotator cuff and Bankart lesion repairs
Authors: Hecker Aaron T. , Shea Marie , Hayhurst John O. , Myers Elizabeth R. , Meeks Louis W. , Hayes Wilson C.
Published: June 2007

Surgical reconstructions of anterior-inferior shoulder instabilities and rotator cuff injuries require secure fix ation of soft tissue to bone. Sutures are inserted directly through transosseous tunnels in current techniques, which are surgically complex and not always adequate for fixation strength. Using fresh-frozen cadaveric hu man specimens, our objectives were 1) to compare immediate pull-out strength of two versions of polyace tal suture anchors (wedge and rod) with conventional suture-only attachment techniques in Bankart lesion and rotator cuff repairs, and 2) to compare pull-out strength of the two polyacetal suture anchors with a metallic suture anchor. Our results indicate no signifi cant differences in fixation strength of Bankart lesions or rotator cuff repairs using sutures only, or using wedge or rod polyacetal suture anchors (P = 0.70). Pull-out force did not differ significantly (P = 0.37) between the two polyacetal anchors. Polyacetal an chors exhibited higher pull-out forces than metallic an chors when inserted into metaphyseal regions of the tibia and significantly higher pull-out forces (P < 0.001) when inserted into metaphyseal regions with thicker cortical walls. Our results indicate that both polyacetal suture anchors provide adequate immediate fixation for soft tissue repairs in the human shoulder.
Detailed Analysis of Patients with Bilateral Anterior Cruciate Ligament Injuries
Authors: Harner Christopher D. , Paulos Lonnie E. , Greenwald Ann E. , Rosenberg Thomas D. , Cooley Vernon C.
Published: June 2007

To better understand anatomic and other possible pre disposing factors for anterior cruciate ligament injuries, we retrospectively studied 31 patients with noncontact, bilateral injuries of this ligament. The 31 patients were carefully matched by age, sex, height, weight, and ac tivity level with 23 control subjects who had no history of knee injury. All 54 subjects underwent a full clinical knee examination, joint hypermobility tests, a hamstring tightness assessment, a computerized tomography scan analysis, and a plain view radiographic analysis, and were asked to provide a complete immediate-family history of knee ligament injury. In addition, the 31 pa tients in the experimental group underwent a KT-1000 arthrometer knee laxity examination and were also asked to provide an injury profile, including mechanism of injury, treatment received for each injury, and the time interval between injuries. Measurements obtained from the computerized tomography scan analysis demon strated a significantly wider lateral femoral condyle in the experimental group compared with the control group, indicating that certain anatomic factors may pre dispose people to anterior cruciate ligament injury. A significant difference was also found in the incidence rate of anterior cruciate ligament injury in the family his tory of the experimental group compared with the con trol group, indicating a possible congenital aspect of this injury.
Evaluation of Patellar Shape in the Sagittal Plane
Authors: Grelsamer Ronald P. , Proctor Christopher S. , Bazos Andrew N.
Published: June 2007

A prospective study of 564 patients was performed to assess the correlation between patellar shape as seen on a lateral radiograph and 1) patellar pain and 2) the radiologic determination of patellar height. A classifica tion of patellar shape was developed based on the ratio of the patellar length to the length of the articular sur face. Three classification types were established, in cluding the "long-nosed," "Cyrano" type. Patients were placed into one of two groups based on the presence or absence of patellar pain. Lateral radiographs were evaluated for patellar height using two published indi ces. A significantly larger portion of Type II and Type III patellae was found in patients with patellar pain. More over, accepted measures of patellar height have to be used with caution in the presence of unusual patellar shapes.
Computerized Tomographic Analysis of Tibial Tubercle Position in the Painful Female Patellofemoral Joint
Authors: Muneta Takeshi , Yamamoto Haruyasy , Ishibashi Toshiro , Asahina Shintaro , Furuya Kohtaro
Published: June 2007

We used computerized tomography to evaluate the po sition of the tibial tubercle and to determine if the tibial tubercle is positioned more laterally in female patients with patellofemoral pain. We also wanted to determine the relationship of the tibial tubercle to tibial external rotation and patellar tilt. Sixty female patients and 19 healthy female controls were evaluated. To evaluate the position of the tibial tubercle, the tibial tubercle rotation angle (the angle formed by the line between the pos teriormost edges of the medial and lateral femoral con dyle and the line between the central point of the in tercondylar space and the central point of the patellar tendon at the level of the tibial tubercle) was measured by superimposing the images from the level of the distal femoral condyle and the tibial tubercle. The relationship between the tibial tubercle rotation angle and patellar tilt was then assessed by dividing the patients into 3 sub groups according to the patellar tilt. The tibial tubercle rotation angle was significantly different between the patellofemoral pain patients and the controls. There were also significant differences between the patients with moderate patellar tilt (10° to 20°) and the controls, and between the patients with high patellar tilt (>20°) and the controls.
Anatomy of the Lateral Ankle Ligaments
Authors: Burks Robert T. , Morgan James
Published: June 2007

The anatomy of the lateral ankle ligaments that is fre quently described in articles and book chapters often lacks the precision of orientation and attachment points. We believe a knowledge of this precise anatomy is im portant to better reconstruct or repair lateral ligaments. We dissected cadaveric ankles free of skin and soft tis sue and made the following measurements: areas of attachments of the anterior talofibular ligament, length and width of the anterior talofibular ligament, and loca tions of the attachments on the fibula and talus. The same measurements were made of the calcaneofibular and posterior talofibular ligaments. The distance of the calcaneofibular calcaneal attachments from the subta lar joint as well as the angle in the sagittal plane with the fibula was determined. We then used these anatomic attachments of the ligaments to make comparisons with the Watson-Jones and modified Elmslie reconstruc tions. Our results enable us to suggest a more anatomic placement for ligaments in a reconstruction.
Neuromuscular Performance in Normal and Anterior Cruciate Ligament-Deficient Lower Extremities
Authors: Wojtys Edward M. , Huston Laura J.
Published: June 2007

The neuromuscular function of the lower extremity in 40 normal and 100 anterior cruciate ligament-deficient vol unteers was evaluated by physical examination, KT- 1000 arthrometer measurements, isokinetic strength and endurance testing, subjective functional assess ment, and an anterior tibial translation stress test. A specially designed apparatus delivered an anteriorly di rected step force to the posterior aspect of the leg while anterior tibial translation was monitored and electro myographic signals were recorded at the medial and lateral quadriceps, medial and lateral hamstrings, and gastrocnemius muscles. Testing was done at 30° of knee flexion with the foot fixed to a scale to monitor weightbearing, while the tibia remained unconstrained. Results indicate that muscle timing and recruitment or der in response to anterior tibial translation are affected by anterior cruciate ligament injury. These alterations in muscle performance change with time from injury, cor relate with an individual's physical activity level, affect subjective functional parameters, and are directly re lated to the degree of dynamic anterior tibial laxity seen with stress testing.
The Effect of Joint-Compressive Load and Quadriceps Muscle Force on Knee Motion in the Intact and Anterior Cruciate Ligament-Sectioned Knee
Authors: Torzilli Peter A. , Xianghua Deng  , Warren Russell F.
Published: June 2007

To determine the effect of an externally applied joint- compressive load and a quadriceps muscle force on knee motion, we tested nine intact cadaveric knees and four knees after sectioning of the anterior cruciate liga ment. Anteroposterior translation was measured at 0°, 15°, 30°, 45°, and 90° of knee flexion after the appli cation of an anteroposterior force of 100 N, a joint- compressive load of 0, 111, 222, 333, or 444 N, and a quadriceps force of 0 or 133 N. Both a joint-compressive load and a quadriceps force significantly decreased to tal anteroposterior translation by as much as 50% to 66% in intact knees and 42% to 71 % in anterior cruciate ligament-sectioned knees. A substantial anterior trans lation was also found with the application of a joint- compressive load or a quadriceps force and no anterior force. We termed this translation an anterior neutral- position shift. The anterior neutral-position shift was sig nificantly greater in the ligament-sectioned knees com pared with the intact knees, so much so that at flexion angles greater than 15°, the application of a 100-N pos terior force could not translate the tibia to the most an terior position achieved in the intact knee with a 100-N anterior force.
The Role of the Long Head of the Biceps Muscle and Superior Glenoid Labrum in Anterior Stability of the Shoulder
Authors: Rodosky Mark W. , Harner Christopher D. , Fu Freddie H.
Published: June 2007

The authors conducted a study to determine if the long head of the biceps muscle and its attachment at the superior glenoid labrum play a role in stability of the shoulder in an overhead position. Their study used a dynamic cadaveric shoulder model that simulated the forces of the rotator cuff and long head of biceps muscles as the glenohumeral joint was abducted and externally rotated. Their data suggest that the long head of the biceps muscle contributes to anterior stability of the glenohumeral joint by increasing the shoulder's re sistance to torsional forces in the vulnerable abducted and externally rotated position. The biceps muscle also helps to diminish the stress placed on the inferior gle nohumeral ligament. Detachment of the superior gle noid labrum is detrimental to anterior shoulder stability as it decreases the shoulder's resistance to torsion and places a greater magnitude of strain on the inferior gle nohumeral ligament.
Anterior Cruciate Ligament Reconstruction with Patellar Tendon
Authors: Graf Ben K. , Henry John , Rothenberg Mitch , Vanderby Ray
Published: June 2007

Patellar tendon grafts used in the reconstruction of the anterior cruciate ligament may be subjected to thou sands of knee flexion-extension cycles during the early postoperative period. The purpose of this study was to model experimentally the patellar tendon graft wear- related damage and failure at the femoral tunnel during simulated knee motion of 0° to 112° of flexion at 1 cycle/ sec. To evaluate the effects of 2 different femoral tunnel orientations, tunnel chamfering, and 3 different graft loads on graft survival, 25 calf femurs and patellar ten dons were used. All 5 specimens with a "straight-line" femoral tunnel and an applied load of 5 pounds (22.3 N) survived greater than 125,000 cycles. All 5 of the 5-pound unchamfered transverse tunnel grafts failed at an average of 19,869 cycles, but chamfering transverse tunnels resulted in the survival of 4 of 5 specimens. Decreasing the load to 2 pounds (8.9 N) for transverse unchamfered tunnels increased survival to 1 of 5, and cycles to failure to 75,132. If patellar tendon grafts used to reconstruct the anterior cruciate ligament are sub jected to large numbers of flexion-extension cycles, the risk of wear-related damage and early failure may be decreased by straight-line femoral tunnel orientation, by chamfering of more transverse tunnels, or by avoiding large graft preloads.
Biomechanical and Histologic Properties of the Canine Patellar Tendon After Removal of its Medial Third
Authors: Linder Lucinder H. , Sukin Dean L. , Burks Robert T. , Haut Roger C.
Published: June 2007

Three groups of dogs were used for this study. All dogs had the medial third of the patellar tendon removed from one knee, while the contralateral knee was used as a control. The time zero group was immediately sacri ficed ; the other two groups were sacrificed at 3 and 6 months. Once the tissues were harvested, the patellar tendon was isolated and biomechanical and histologic analyses were conducted. Three and 6 months after surgery, there was a large amount of visible scar tissue in the tendon. The cross-sectional area of the tendons was 275% and 288% of controls at 3 and 6 months, respectively. The tensile modulus of the tendon was statistically less than controls at both 3 and 6 months. The energy to failure and stiffness of the operated ten dons were not statistically different than controls at 3 or 6 months after surgery. The results of this study directly contrast with those of an earlier study on the removal of the central third of the patellar tendon. While a number of factors could explain differences observed between removal of a central or medial third, this study confirms the short-term damaging effects of surgical removal of a portion of the patellar tendon to reconstruct a torn anterior cruciate ligament.
Measurements of the Intercondylar Notch by Plain Film Radiography and Magnetic Resonance Imaging
Authors: Herzog Richard J. , Silliman James F. , Hutton Kirk , Rodkey William G. , Steadman J. Richard
Published: June 2007

The purpose of this investigation was twofold. In Part I, we determined the accuracy of morphometric analysis of the knee using magnetic resonance imaging and plain film radiography. The results of Part I validated the accuracy of magnetic resonance measurements and its superiority over plain film measurements. In Part II, we evaluated knee morphometry in 20 asymptomatic ath letes with chronic anterior cruciate ligament insuffi ciency to determine if any predisposing factors to an terior cruciate ligament disruption could be detected. With our analysis, we could detect no predisposing fac tors to explain the anterior cruciate ligament disruption in the cohort group.
Effect of an Ankle Orthosis and Ankle Ligament Anesthesia on Ankle Joint Proprioception
Authors: Feuerbach Jon W. , Grabiner Mark D. , Koh Timothy J. , Weiker Garron G.
Published: June 2007

The purposes of this study were to determine the effect of a rigid ankle orthosis (Aircast Air-Stirrup) and lateral ankle ligament anesthesia on ankle joint proprioception. Twelve noninjured subjects attempted to match nine reference ankle joint positions with their eyes closed before and after application of the ankle brace and be fore and after one or two of the lateral ankle ligaments (anterior talofibular and calcaneofibular) were anesthe tized. Three-dimensional ankle joint orientations were recorded with a Motion Analysis system.

No significant differences in the constant, variable, or absolute error were seen between subjects in the non- anesthetized and anesthetized conditions (P > 0.05), regardless of whether one or two ligaments were anes thetized. Thus, it appears that ligament mechanorecep tors contributed little to ankle joint proprioception, and that the afferent feedback from skin, muscle, and other joint receptors was adequate for the positioning task of the present study. Both the variable and absolute error in matching the reference positions were significantly less with the orthosis than without (P < 0.05). Applica tion of an orthosis may increase the afferent feedback from cutaneous receptors in the foot and shank, which may in turn lead to an improved ankle joint position sense.
Stress Fractures of the Femoral Shaft in Athletes—More Common Than Expected
Authors: Johnson Alan W. , Weiss Carl B. , Wheeler Donald L.
Published: June 2007

Athletes from 20 Division I AA collegiate varsity sports and 1 club sport were followed carefully for the devel opment of stress fractures during the 1990 to 1991 and the 1991 to 1992 academic years. During this period, among 914 athletes, 34 stress fractures were sus tained. Seven of these, or 20.6%, were of the femoral shaft. This represents a much higher incidence than previously observed in athletes. A new clinical test is described that significantly aids in the early diagnosis and follow-up treatment of femoral shaft stress fractures.
Identification of a Threshold for Skeletal Muscle Injury
Authors: Noonan Thomas J. , Best Thomas M. , Seaber Anthony V. , Garrett William E.
Published: June 2007

This study was designed to detect the first evidence of injury to muscle induced by passive stretching. Rabbit extensor digitorum longus and tibialis anterior skeletal muscles were subjected to passive stretching at set force levels of 20% or 30% of load to failure. Both tibialis anterior and extensor digitorum longus muscles that were stretched to 30% exhibited no difference in the three tensile parameters when compared with their con tralateral control specimens. Maximum contractile force was decreased after stretching. Tibialis anterior and ex tensor digitorum muscles that were stretched to 20% of control failure force showed no decrement in the tensile parameters or maximum contractile force. Histology of the extensor digitorum longus muscles stretched to 30% of failure force showed small focal areas of muscle fiber rupture and hemorrhage near the distal myoten dinous junction. Tibialis anterior and extensor digitorum longus muscle-tendon units stretched to 30% of failure force suffered functional injury as their contractile ability decreased after stretching. In contrast, muscle-tendon units stretched to 20% of failure force suffered no dec rement in contractile ability; therefore, a threshold for passive muscle stretch injury has been found. Further more, changes in contractile properties and histologic assessment appear to be more sensitive predictors of injury than measurement of structural failure properties.
Hamstring Injuries in Sprinters
Authors: Jonhagen Sven , Nemeth Gunnar , Eriksson Ejnar
Published: June 2007

Eleven sprinters with recent hamstring injuries were compared with nine uninjured runners. The flexibility of the hamstrings and the eccentric and concentric muscle torque were measured in the hamstrings and quadriceps muscles at different angular velocities. Sprinters with a previous hamstring injury had signifi cantly tighter hamstrings than uninjured sprinters had. The uninjured sprinters had significantly higher eccen tric hamstring torques at all angular velocities. They also had significantly higher concentric quadriceps and hamstring torques at 30 deg/sec but not at higher velocities. Sprinters with a history of hamstring injury thus differed from uninjured runners, being weaker in eccentric contractions and in concentric contractions at low velocities.