Left Knee Pain After Anterior Cruciate Ligament Reconstruction - Page #4

Working Diagnosis:
Left thigh pain due to semitendinosus muscle retraction with sensory symptoms due to sciatic nerve irritation.

Physical therapy was prescribed for eight sessions

After physical therapy, the patient reported minimal improvement in pain and decreased muscle tightness was noted by the therapist after his course was completed. He was discharged to a home exercise program and continued his usual activities with some decreased pain but still reported symptoms. In view of his continued sensory symptoms, it was recommended that he have electrodiagnostic testing but he defaulted from follow-up before testing could be performed or any other treatment instituted.

Author's Comments:
The gold standard in graft choice for anterior cruciate ligament reconstruction is the bone-patellar tendon-bone autograft. However, the morbidity associated with this procedure such as patellofemoral pain and difficulty kneeling has led to hamstring autograft being a popular alternative. The postoperative outcome is reported to be similar for both types of autograft.1 Although the muscles retract and shorten after harvest, it has been found in several studies that the hamstring tendons regenerate after harvest and this seems to occur in at least 75% of patients.2,3 It has been found that there is decreased volume and peak cross-sectional area of the gracilis and semitendinosus and compensatory hypertrophy of the biceps femoris and semimembranosus muscles.4 In a study a minimum of 6 years after ACL reconstruction, it was found that the insertion point of the regenerated tendons was almost at the normal anatomical point.3 Muscle retraction was greater when there was no tendon regeneration. The relationship between knee flexion strength and tendon regeneration has been controversial in the literature.2,5 It is also conceivable that internal rotation could be affected by hamstring tendon harvesting. To the best of our knowledge, there have been no previous reports of chronic thigh or knee pain related to retraction of the hamstring tendons without regeneration.

Editor's Comments:
Ultrasonography is a useful tool that can provide significant information regarding an unsuccessful regeneration of the semintendinosis tendon. Another radiographic tool that can be used would be a 3-dimensional computed tomograhy providing more detailed morphological information than the conventional magnetic resonance image. Electrodiagnostic studies should be pursued in the patient with unresolved symptoms to help delineate and classify the nerve injury. A cadaveric anatomic study done by Egan et al looked at the anatomic relationship with the sciatic nerve and the semitendinosus tendon from the posterior aspect and postulates that the distance between the two structure may be not be as consistent more proximally. Thus, the sciatic nerve may be at higher risk during harvesting due to this inconsistency.

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