Quadriceps and Hamstring Muscle Strength Recovery After a Multiligament Knee Injury: A Long-term Follow-up

Multiligament knee injuries (MLKIs) are serious and heterogeneous injuries that often lead to long-term functional limitations. There is limited literature regarding objective muscle strength and functional recovery after surgical treatment of MLKIs.

To investigate long-term quadriceps and hamstring muscle strength and functional recovery after surgical treatment of MLKI and to compare postoperative outcomes between single cruciate MLKI and bicruciate MLKIs.

Cross-sectional study; Level of evidence, 3.

Patients surgically treated for an MLKI at a single level 1 trauma center between January 2013 and December 2020 were included. Isokinetic quadriceps and hamstring muscle strength were assessed using a Biodex dynamometer, and physical function was measured by single-leg hop, triple hop, crossover hop, and 6-m timed hop tests, with the limb symmetry index (LSI) calculated.

Of 124 eligible patients, 90 (72%) participated at a mean follow-up time of 7 years (SD, 2.1) since surgery to evaluation. The median age at the time of testing was 49 years (range, 21-72) and 59% were male. In total, 54% of the patients had not regained full quadriceps strength (LSI <90%), and 46% had persistent hamstring deficits for peak torque/body weight (PT/BW) at 60 deg/s. Across the entire cohort, there was a significant difference between the uninvolved and involved sides for quadriceps and hamstrings for PT/BW (P = .01). The mean LSI for quadriceps PT/BW was 88% at 60 deg/s and 90% at 240 deg/s, while for the hamstrings, the mean LSI was 93% at 60 deg/s and 97% at 240 deg/s. Median LSIs for the hop tests ranged from 93% (range, 41%-187%) for single leg to 99% (42%-141%) for crossover; however, 44% of patients failed to reach the 90% threshold for the single-leg hop. The 6-m timed hop test and quadriceps muscle strength were significantly lower for patients with bicruciate injuries than those with single cruciate injuries (P < .05).

Persistent deficits in quadriceps and hamstring muscle strength were observed 7 years after MLKI surgery, with a substantial proportion of patients failing to regain full functional symmetry in muscle strength and hop test performance. Patients with bicruciate injuries demonstrated significantly more pronounced deficits in muscle strength and hop test scores as compared with those with single cruciate injuries.