Introduction: The aim of our study was to: 1) compared the objective and subjective outcome of anterior cruciate ligament (ACL) reconstruction to data in the literature, 2) assess the correlation between objective parameters and subjective outcomes (ACL) reconstruction, 3) asses the differences in muscular status between normal (⡥15 percentile IKDC normative value) and subnormal (<15 percentile IKDC normative value) patients and 4) test different neuro-muscular parameters as possible predictors for good subjective outcome. In the literature there are no published studies to compare neuro-muscular characteristics (Tensiomyography (TMG), isokinetic testing) between patients with normal and subnormal short-term subjective outcome.
Methods: Sixty patients after primary anatomical single-bundle hamstring ACL reconstruction were prospectively enrolled. 1) Demographics, subjective, clinical, and functional status of the injured knee were recorded at baseline, 6, and 12 months post-operatively. We compared the acquired parameters with results from the literature. 2) We analyzed the parameters in tried to find correlations between subjective outcome and objective clinical knee joint status. 3) The patients were assigned into normal or sub-normal outcome group based on their IKDC scores at 6 months. TMG and isokinetic dynamometry of thigh muscles were performed and compared between the groups. 4) We determined muscular predictive factors for higher IKDC and Lysholm score as well as higher Tegner level of activity at 12 months after surgery
Results. 1) Our patients had an average age of 31,8 years, preoperative IKDC of 55,4 and instrumental instability (KT-1000) of 3,3 mm. Our results were similar to published data. 2) We noticed only minor correlations between the single-leg hop test and IKDC score and Lysholm score. There were no important correlations between the objective clinical knee status and subjective outcome. 3) At 6 months’ timeline, 21 patients (35%) perceived their knee function as normal, while 39 (65%) were sub-normal. There were no differences in clinical status of the knee between both groups but patients in normal group achieved higher IKDC, Lysholm, Tegner scores as well as longer single-leg hop test. TMG revealed higher biceps femoris as well as semitendinosus and semimembranosus radial displacement values on the operated leg in normal group (BF=7,0 mm in ST+SM=9,9 mm). Isokinetic dynamometry showed significantly higher normalized peak torque (2,44 Nm/kg) and average power (133,0 W) of knee extensor muscles. 4) Biceps femoris displacement and extensor peak torque are positive predictive factors for higher IKDC score and higher Tegner activity level at 12 months
Conclusions: Our study confirmed a significant progress of patients’ subjective and objective parameters during the follow-up period. Our results are similar to those published in recent literature. There were no significant correlations between objective clinical knee joint status and subjective outcome after ACL reconstruction. Patients who perceive their knee function as normal at six-months following ACL reconstruction presented with better neuromuscular properties of the thigh muscles. Decreased hamstring stiffness and higher peak torque of extensor muscles seem to have a profound impact on better subjective outcome and higher activity 1 year after surgery as well as shorter time of returning to preinjury activity. Our research showed that thigh muscle status 6 months after surgery is in significant co-dependence with subjective outcome following ACL reconstruction and a predictive factor for subjective outcome after 1 year.
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