The Effect of Patellar Eversion on Functional Outcomes in Primary Total Knee Arthroplasty

Study Overview
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Brief Summary
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Short and long term outcomes of total knee arthroplasty patients surgically exposed with patellar eversion are compared to those patients exposed by laterally retracting the patella. It was hypothesized that there would be no difference.

Detailed Description
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Background: Patellar mobilization during total knee arthroplasty (TKA) has been debated, with some proponents of minimally invasive TKA suggesting that laterally retracting, rather than everting the patella may be beneficial. It was our hypothesis that by using randomized, prospective, blinded study methods, there would be no significant difference in clinical outcome measures based solely on eversion of the patella during total knee arthroplasty. Methods: After an a priori power analysis was done, 120 primary total knee replacements indicated for degenerative joint disease were included in the study and randomized to one of two patella exposure techniques: lateral retraction or eversion. Collaborating investigators and patients were blinded to randomization.

Official Title
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A Randomized, Controlled, Prospective Study Evaluating the Effect of Patellar Eversion on Functional Outcomes in Primary Total Knee Arthroplasty.

Conditions
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Total Knee Replacement, Arthroplasty, Patella

Intervention / Treatment
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* Procedure: Primary Total Knee Replacement Surgery


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients eligible for study participation included all comers for primary total knee arthroplasty indicated for degenerative joint disease. All operations were performed by three well-established arthroplasty-fellowship-trained orthopaedic surgeons using surgical techniques based on that of a senior surgeon. All implanted devices were cruciate-substituting tricompartmental total knee replacements placed through a medial parapatellar approach. All patients were anaesthetized with spinal anesthesia, received a peri-operative cocktail injection, and had tourniquet times between 0 and 120 minutes. Multi-modal post-operative pain management and accelerated physical therapy were performed as previously described. Exclusion Criteria: Patients were excluded from the study if on the operative side they had undergone prior total knee replacement, prior knee arthrotomy, prior osteotomy at or about the knee, or had preoperative angular deformity greater than 20 degrees.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Patellar Eversion<br>Patients randomized to the Patellar Eversion arm of the study were surgically exposed by everting the patella during their Primary Total Knee Replacement Surgery. | Procedure: Primary Total Knee Replacement Surgery<br>* Patients randomized to the eversion group had patellas everted during the flexion portions of the surgery. Patients randomized to the retraction group had patellas everted only for the patellar resurfacing portions of the surgery. Both groups were mobilized with anterior tibial translation. All other aspects of surgery including postoperative care, anticoagulation, pain control, and physical therapy were done as per standard arthroplasty protocols at our institution.<br>|
| Active Comparator: Patellar Lateral Retraction<br>Patients randomized to the Patellar Lateral Retraction arm of the study were surgically exposed by laterally retracting the patella during their Primary Total Knee Replacement Surgery. | Procedure: Primary Total Knee Replacement Surgery<br>* Patients randomized to the eversion group had patellas everted during the flexion portions of the surgery. Patients randomized to the retraction group had patellas everted only for the patellar resurfacing portions of the surgery. Both groups were mobilized with anterior tibial translation. All other aspects of surgery including postoperative care, anticoagulation, pain control, and physical therapy were done as per standard arthroplasty protocols at our institution.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in quadriceps strength | Quadriceps strength was measured isometrically using a Biodex dynamometer with the patient's knee in 60 degrees of flexion. | preop, 6 weeks, 3 months, 1 year postop | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| change in ability to perform straight leg raise | For the purposes of this study, we defined the ability to straight leg raise as a patient independently raising their heel 6 inches off of the bed with foot dorsiflexed and knee fully extended without extension lag. | up to three days postop | 
| change in Visual Analog Scale of Pain | Patient reported pain using standardized VAS diagram | preop, up to 3 days postop, 6 weeks, 3 months, and 1 year postop | 
| change in Ambulation Distance |  | up to 3 days postop | 
| Length of Hospital Stay |  | expected average 2 to 3 days | 
| change in SF-36 score |  | preop, 6 weeks, 3 months, 1 year postop | 
| change in Range of knee motion | goniometer used to standardize measurements | preop, 6 weeks, 3months, 1 year | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Total Knee Replacement, Patellar Eversion, Surgical Exposure, Outcomes, Quadriceps Strength, Straight Leg Raise, SF-36