Comparison of Short-Term Biodex Results after Anatomic ACL Reconstruction Between Three Autografts
Authors: Hughes Jonathan Daniel , Burnham Jeremy M. , Hirsh Angela , Musahl Volker , Fu Freddie H. , Irrgang James J. , Lynch Andrew D. 
Published: July 2018

Objectives:

Recent literature has suggested residual quadriceps weakness up to 12 months after anterior cruciate ligament reconstruction (ACLR), especially with quadriceps tendon autograft. These studies, though, have not directly compared different autograft options. The primary objective of this study was to compare short-term quadriceps and hamstring muscle strength between individuals undergoing primary ACLR with quadriceps tendon (QT), bone-patellar tendon-bone (BPTB), or hamstrings tendon (HS) autograft. The secondary objective was to assess how patients performed relative to common clinical strength thresholds used for return to activity decisions. We hypothesized that QT autografts would have poorer quadriceps strength symmetry at 5-8 months as compared to HS and BPTB, but there would be no significant difference at 9-15 months among all three groups.

Methods:

Patients who underwent anatomic primary ACLR with autograft at one institution from 2010-2015 were retrospectively reviewed. Isometric quadriceps and hamstrings strength measurements were routinely obtained between 5-8 months and 9-15 months postoperatively in these patients. To normalize strength outcomes between participants, we created a quadriceps (QI) and hamstring (HI) strength indices by expressing the ACLR limb strength as a percentage of the uninvolved limb strength. Values less than 100% indicated a strength deficit, while values greater than 100% indicated greater strength in the ACLR limb. Patients could be cleared to run if strength symmetry exceeded 80% and cleared to play if quadriceps strength symmetry exceeded 90%.

Results:

A total of 73 patients were identified with 5-8 month follow up, and 52 patients with 9-15 month data (Table 1). The QT group had significantly lower QI at 5-8 months (69.5 ± 17.4) as compared to the BPTB (82.8 ± 14.6, p = 0.01) and HS (86.0 ± 18.6, p < 0.01) groups. Similarly, the HS group demonstrated a significantly lower HI at 5-8 months (79.5 ± 14.6) compared to the BPTB group (98.0 ± 17.5, p < 0.01). However, there was no significant difference when compared to the QT group (88.4 ± 17.4, p = 0.06). At 5-8 months, more patients with HS autograft met criteria to return to run and play (84% and 26%, respectively) compared to QT (26% and 13%, respectively). In the 9-15 month analysis, the HS group had a significantly lower HI (84.2 ± 23.1) compared to the QT group (99.8 ± 20.1, p = 0.03), but no difference was noted when compared to the BPTB (99.6 ± 17.6, p = 0.08) group. There was no significant difference in quadriceps strength symmetry between the QT (83.3 ± 20.7), BPTB (97.0 ± 13.8), and HS (90.0 ± 17.5) groups at 9-15 months (p = 0.13). Additionally, there was no significant difference in percent of patients that met return to play and return to run thresholds between groups at 9-15 months.

Conclusion:

In conclusion, patients undergoing ACLR with QT demonstrated clinically meaningful quadriceps asymmetry, and patients reconstructed with HS had significant hamstring asymmetry at 5-8 months and 9-15 months postoperatively. Additionally, significantly fewer patients in the QT group met criteria to return to play and run at 5-8 months than the BPTB and HS groups. No significant difference was found at 9-15 months in regards to QI and return to play and run criteria between all three groups. These data suggest a longer time to return to play and specific rehabilitation protocols that emphasize quadriceps strengthening may be necessary due to residual quadriceps weakness after ACLR with QT. [Table: see text]