ABSTRACT
PURPOSE OF THE STUDY: The purpose of this study was to investigate isokinetic performance of the knee twelve months after ligamentoplasty of the anterior cruciate ligament using four-strand hamstring autografts. We wanted to ascertain the effect of exercise-induced postoperative pain. MATERIAL AND METHODS: Between January 2001 and January 2003, at total of 75 patients underwent arthroscopic hamstring ligamentoplasty performed by the same surgeon. Isokinetic measurements were obtained at 4, 6, and 12 months postoperatively. At four months, four subpopulations were identified depending on the presence or not of exercise-induced pain. RESULTS: Fifty-two patients were pain free, seven presented exercise-induced posterior pain, nine exercise-induced anterior pain and seven diffuse pain with more than 5 degrees limitation of extension and 10 degrees for flexion. Isokinetic measurements at an angular speed of 60 degrees /s performed at the fourth postoperative month were compared with the pain-free population and demonstrated a significant flexion deficit in patients with exercise induced posterior pain (32% vs 18%, p = 0.04), significant extension deficit in patients with exercise-induced anterior pain (45% vs 30%, p = 0.02), and significant deficit in extension (58% vs 30%, p = 0.001) and flexion (39% vs 18%, p = 0.01) in patients with diffuse pain and limited joint motion. Certain deficits persisted one year after surgery. Patients did not achieve their prior level in contact pivot sports if they presented exercise-induced anterior pain. The population with diffuse pain and limited joint motion only resumed line sports. DISCUSSION: It is not easy to ascertain the origin of knee pain after ligamentoplasty. Posterior pain at the harvesting site occurs after hamstring reconstruction (defective regeneration or incomplete disinsertion with muscle retraction). The hamstring technique can also lead to anterior pain involving all the structures of the extension system. Diffuse pain with limited joint motion is related to "minor" reflex dystrophy. CONCLUSION: A mean 10% extensor and flexor isokinetic deficit can be expected one year after four-strand hamstring ligamentoplasty. Isokinetic tests performed four months postoperatively in patients with exercise-induced pain can provide objective evidence of difficult recovery. Posterior exercise-induced pain is associated with a flexion deficit of more than 30%. Anterior pain with exercise is associated with 45% deficit in extension. Diffuse pain with limited joint motion is associated with more than 40% in flexion and more than 55% in extension. These quantitative results enable the surgeon to inform the patient concerning potential sports level after repair since recovery will be longer with greater deficit.
