More than 100,000 anterior cruciate ligament reconstruction operations are performed annually in the United States1. Autogenous bone-patellar tendon-bone graft is the most frequent graft option used. The reported prevalence of complications varies widely, and serious complications include infection, stiffness, graft failure, deep venous thrombosis, tendon rupture, osteonecrosis, and periarticular fracture2-6. Periarticular fractures associated with anterior cruciate ligament reconstruction have been reported and include patellar, tibial plateau, tibial tubercle, and lateral femoral condylar and supracondylar femoral fracture patterns. Patellar fracture has been the most commonly documented postoperative fracture complication and occurs in conjunction with the harvesting of autogenous bone-patellar tendon-bone graft7,8. Additionally, eight tibial fractures9-16 and eight lateral condylar or supracondylar femoral fractures associated with anterior cruciate ligament reconstruction have been reported17-24. These fractures occurred through iatrogenic stress-risers25,26 created at the time of reconstruction, and the reported treatment had been arthrotomy with open reduction and internal fixation.
To our knowledge, the case of our patient represents the first published report of medial femoral condylar fracture occurring after arthroscopic anterior cruciate ligament reconstruction and the first report of the use of arthroscopically assisted medial femoral condylar reduction and percutaneous internal fixation. Arthroscopically assisted reduction with internal fixation of a displaced lateral condylar fracture has been reported rarely27-29; however, to our knowledge, a similar approach to a medial condylar fracture has not been reported.
In the case of our patient, the mechanism of injury causing the medial femoral condylar fracture appeared to be the direct impact onto the medial femoral condyle of a flexed knee during a fall. Similar to the other reported femoral fracture patterns, this fracture occurred through the femoral tunnel stress-riser that had been created during the anterior cruciate ligament reconstruction. The patient was informed that data concerning the case would be submitted for publication, and he consented.
A forty-one-year-old man presented to our orthopaedic clinic with a history of chronic pain and instability of the right knee. The surgical history included an extra-articular MacIntosh-type reconstruction eighteen years earlier, which had been performed as treatment for a deficient anterior cruciate ligament. Hardware had been removed secondarily. The patient reported that after a satisfactory result for many years, increasing pain and instability slowly developed in the right knee, causing him to begin wearing a knee brace. The physical examination revealed a positive Lachman test, without an end point, and a painful positive pivot-shift test. Absence of the anterior cruciate ligament, grade-III chondromalacia of the lateral femoral condyle, and a posterolateral meniscal tear were documented on magnetic resonance imaging of the right knee. No screw-holes or bone defects from previous surgery were identified.
The patient underwent reconstruction of the anterior cruciate ligament. Intraoperative procedures included a subtotal posterior horn meniscectomy plus an abrasion chondroplasty and microfracture for a small but severe area of chondromalacia of the lateral femoral condyle. A standard notchplasty was followed by arthroscopic anterior cruciate ligament reconstruction with use of bone-patellar tendon-bone allograft. A femoral tunnel (12 mm in diameter, 30 mm deep) was then made after placement of a guide pin at approximately the eleven o'clock position with a 7-mm offset guide. This left an intact 1-mm posterior cortex in the femoral tunnel. A 12-mm-long tibial tunnel was placed 7 mm anterior to the tibial insertion of the posterior cruciate ligament. A bone-patellar tendon-bone allograft (12 mm in diameter) was passed into the knee through the tibial tunnel and was fixed under tension. Femoral fixation with two 2.7-mm bioresorbable cross-pins (RIGIDfix; DePuy Mitek, Raynham, Massachusetts) was followed by tibial fixation with a bioresorbable 12-mm-diameter × 28-mm-long interference screw (DePuy Mitek). There were no intraoperative complications, and the patient was instructed to remain non-weight-bearing on crutches to protect the abrasion chondroplasty.
Six weeks postoperatively, the patient reported losing his balance and falling while descending a short flight of stairs with the use of crutches. Examination in the emergency department revealed diffuse swelling in the right knee and painful osseous crepitus when the knee was flexed. A contusion was noted at the point of impact over the distal end of the medial femoral condyle. The neurologic and vascular examinations revealed normal results. Radiographs revealed a displaced fracture (AO/OTA type-33-B230) of the medial condyle of the femur (Figs. 1-A and 1-B). Computed tomography showed the sagittal intracondylar fracture line exiting through the femoral bone tunnel (Fig. 2). No osteolysis was identified within the femoral tunnel, and no cross-pin fixation bone tunnels were identified.
Treatment consisted of fluoroscopic navigation plus arthroscopically assisted closed anatomic reduction of the fracture and percutaneous fixation with four 7.3-mm-diameter cannulated screws and washers (Synthes, Paoli, Pennsylvania). The operative setup entailed both arthroscopic visualization and fluoroscopic navigation. The patient was placed in a supine position on a radiolucent table. The end of the table was removed to allow c-arm access and to facilitate manipulation of the extremity. Standard anterolateral and anteromedial arthroscopic portals were established. Arthroscopic lavage and débridement of the hematoma was followed by direct visualization and débridement of the fracture site prior to closed reduction. Longitudinal traction on the limb with the knee in mild flexion and with valgus manipulation allowed the medial femoral condylar fragment to be pulled into proper alignment with ligamentotaxis. Two 2.8-mm-diameter guidewires for the 7.3-mm-diameter cannulated screws were inserted percutaneously into the medial condylar fragment to manipulate it. With use of both guidewires (one in each hand), the proximal aspect of the medial condylar fragment was manipulated into its origin on the distal aspect of the femur and held in place. The distal body of the fragment was then reduced anatomically with the distally placed guidewire. Combined fluoroscopic and arthroscopic visualization of the fracture site confirmed an anatomic reduction. Provisional fixation of the reduction was then obtained as the 2.8-mm guidewires were driven across the fracture. Fracture-fragment compression was observed arthroscopically as the screws were tightened over the guidewires (Fig. 3), and anatomic reduction and fixation were confirmed radiographically (Figs. 4-A and 4-B).
Arthroscopy also provided visualization of the intact anterior cruciate graft during intraoperative stability testing after reduction and fixation of the fracture. Both the Lachman test and stability testing with a nerve-hook probe demonstrated graft stability that was unchanged in comparison with the stability noted at the completion of the anterior cruciate ligament reconstruction.
Postoperatively, the patient was at first restricted to non-weight-bearing on crutches and was then allowed to gradually begin range-of-motion and then strengthening exercises. Graduated weight-bearing was begun at six weeks. At twelve weeks after fracture repair (eighteen weeks after anterior cruciate reconstruction), the patient had achieved a full range of motion of 0° to 140°. He was bearing full weight, the KT-1000 arthrometer testing and Lachman tests were classified as grade A according to the system of the International Knee Documentation Committee31, and the pivot-shift test was negative. At no time was posterior, varus, or valgus instability detected, and there was no subjective instability. Radiographs showed that the fracture had healed in excellent alignment.
Periarticular fracture of the knee is an uncommon complication of anterior cruciate ligament reconstruction. To date, to our knowledge, there have been no reports of medial femoral condylar fracture after arthroscopically assisted anterior cruciate ligament reconstruction. In our patient, the impact force from the fall was directed to the medial side of the flexed knee, thus resulting in a fracture of the medial condyle through the femoral tunnel stress-riser.
A review of the literature with regard to periarticular fracture of the knee after anterior cruciate ligament reconstruction revealed that most fractures are associated with trauma in association with an iatrogenic stress-riser. These stress-risers occur as a result of bone tunnels, autograft host defects, and cortical defects from extra-articular fixation7-24. It has been shown that a drill-hole can elevate stress concentration and result in a fracture through the drill-hole25,26.
One report described a lateral femoral condylar fracture after anterior cruciate ligament reconstruction in which the femoral tunnel was overdrilled and violation of the lateral femoral cortex resulted in the creation of a stress-riser22. Two other case reports described supracondylar and lateral femoral condylar fractures through femoral tunnel stress-risers17,21. The four remaining distal femoral fractures (two lateral condylar fractures, one supracondylar fracture, and one distal femoral shaft fracture) occurred through a femoral tunnel stress-riser18, an extra-articular fixation site for a prosthetic graft20, an iliotibial tenodesis screw fixation site19, or a ligament augmentation device site24.
Our patient underwent bioresorbable 2.7-mm cross-pin fixation through the femoral tunnel and graft. We were unable to identify the cross-pin bone tunnels on the postinjury computed tomography scan. The femoral fracture exited through the inferior and medialmost aspect of the femoral tunnel and not through the cross-pin tunnels.
Preoperatively, we did not find a distal medial femoral condylar plate designed for fixation of this fracture type. All condylar plates currently available are contoured to fit the lateral femoral condyle. Although a T-buttress plate could have been bent into a modified shape in an attempt to contour it to the medial femoral condyle through an incision and arthrotomy, we chose to proceed with operative repair of the fracture with arthroscopically assisted closed reduction and percutaneous screw fixation. Case reports of this technique for lateral femoral fracture repair are rare27-29. Its benefits include the enhanced ability of the surgeon to achieve an excellent intra-articular reduction and decreased blood loss. The minimal amount of soft-tissue dissection may lead to a more rapid postoperative recovery. Additionally, if difficulty is encountered with this technique, the surgeon still has the option of switching to the more standard procedure of open reduction and internal fixation. This less invasive technique can provide a good clinical result, and we believe it should be considered as one way to treat this type of intra-articular fracture. 