Valgus loading of the knee joint with or without rotational forces is generally accepted as a mechanism of medial collateral ligament (MCL) and/or anterior cruciate ligament (ACL) injury. Considering this mechanism of injury and an athlete's report of hearing a "pop" an MCL/ACL injury would likely be high on the athletic trainer's index of suspicion. In the child or adolescent athlete, however, there may be an associated or, alternately , an isolated epiphyseal farcture. Injuries at the distal femoral physis commonly cause growth disruption and may result in leg-length discrepancy. It is very important for athletic trainers to be aware of this injury, since at least half of all injuries at this site occur during sports activities. Physeal injury must be included in the differential evaluation of adolescent knee injuries. The following case report highlights the clinical features of a distal femoral epiphyseal injury.
A 14-year-old male (6 ft, i in; 180 lb) football player sustained a valgus blow to his left knee during a football game. He reported hearing apop at the time of the blow and another upon hitting the ground, He described the sensation occurring with the second pop as "like something fell back in place." He noted immediate swelling and pain throughout the knee, and was unable to bear weight, After a brief evaluation by his coach, the athlete was evacuated from the field by ambulance.
Upon examination in the emergency room, the athlete was anxious but not in distress. There was a moderate knee effusion, no obvious deformity, and neurovascular function of the leg was normal. He was having some pain at rest. There was tenderness along the medial side of the knee, just proximal to the joint line, extending into the metaphysis. Lachman and valgus testing of the knee were intolerable;however, the knee was not grossly unstable.
Because of the mechanism of injury, the area of tenderness,and the presence of extra-articular swelling, an epophyseal injury was suspected. X-rays were positive for a fracture through the medial distal femoral physis and epiphysis extending into the knee joint through the intercndylar notch(Figs 1 & 2 ). There was a 2-to3-mm displacement of the fragment. This injury was classified as a Salter-HarrisIII fracture(Fig 3). Theathlete's x-rays were also significant in that they showed him to be near skeletal maturity despite his youg chronological age. His past medical history was positive for an alleged mild sprain of his left anterior cruciate ligament the previous winter,and a well-healed feft distal fibula fracture at age 10. He had no continuing complaints related to either jnjury.
The athlete was brought to the operating room where he was anesthetized and 120 cc of blood was aspirated from the knee joint. A gentle Lachman test revealed 5 mm of laxity, with a good end point. Varus stress testing, applied to check theintegrity of the lateral collateral ligament, was normal. Other ilgament testing was defered. The fracture was reduced by closed manipulation. Confirmation of satisfactory reduction was obtained by intraoperative fluoroscopy reduction was obtained by intraooperative fluorocopy and was followed by internal fixation using a 7.5-mm screw placed percutancously , medial to lateral, through the condyles, and a smooth pin placed distal to proximal and posterior to anterior across the growth plate (Fig 4). The incisions were dressed and bandaged and the leg was placed in a long-leg fiberglass cast. The athlete was limited to toe-touch weight bearing with crutches.
After 2 weeks, the cast was replaced with a rehabilitation brace set at o' . The athlete was instructed to begin a home program of quad ses and gentle short-arc range-of-motion exercises. After 3 weeks, the smooth pin was removed in the office, the brace was set to allow 0' to45' of motion, and he was referred for supervised physical therapy. During 3 weeks of therapy, his status improved to full weight bearing, range of motion 0' to 120'. His exercise program included stationary cycling, stair machine, mini-squats, lunges, step-ups, step-downs, and discharged from supervised physical therapy to continue strengtherning and low-impact/pool exercise independently.