Keywords
allografts - femoral fractures - knee dislocation - osteochondritis
Introduction
Hoffa fracture (HF) involves the posterior femoral condyle in the sagittal plane, and it has an estimated incidence of 0.65% among femoral bone fractures.[1] It typically occurs after axial load force over the distal third of the femur with the knee positioned in more the 90° of flexion. The lateral femoral condyle (LFC) is often affected in high-energy trauma, and previous valgus limb alignment might be associated with HF at the LFC.[2] However, it has also been reported at the medial femoral condyle (MFC).[1]
Anatomic reduction and stable fixation must be prioritized during the surgical approach to HF in order to achieve early joint mobility and decrease the rate of post-traumatic arthritis. Non-anatomical reduction and additional chondrocyte apoptosis are associated with high rate of articular degenerative changes in young patients. The technique of transplantation of osteochondral allografts (OCAs) represents a reasonable surgical approach to repair the anatomy of the chondral surface and restore associated bone loss.[3] Recently, OCAs have been gaining popularity, and have been used in post-traumatic osteoarthrosis (OA), complex fractures, and malunion around the knee joint.[3] The present case report aims to describe an OCA transplant selected as a surgical approach in a complex HF during a motor-vehicle high-energy trauma.
Case Report
A 27-year-old patient was first admitted to a secondary regional trauma center after being involved in a motor-vehicle accident. The case reported was previously approved by the Institutional Review Board (CAAE: 46596721.2.0000.5273). The radiologic assessment confirmed a right calcaneus fracture, left femoral head fracture, and ipsilateral medial knee dislocation. The clinical examination confirmed a grade-III medial collateral injury, grade-III posterior cruciate ligament lesion, and complete anterior cruciate ligament (ACL) tear, which led to the clinical diagnosis of knee dislocation. The physical examination showed a regular lower-limb pulse and intact nerve function.
A computed tomography (CT) scan of the right knee revealed a complex medial HF – grade 33 B3 according to the classification of the Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association (AO/OTA) ([Fig. 1 A-B]). Issues such as non-anatomical reduction, post-traumatic OA, and traumatic chondrocyte apoptosis led the senior surgeon to choose allograft tissue transplantation. At the time of the treatment, our group[4] had previously tested and approved an osteochondral-preservation protocol.
Fig. 1 (A) Three-dimensional reconstruction of a preoperative sagittal computed tomography scan. (B) Preoperative axial computed tomography scan.
A left-knee posteromedial approach was selected for the surgical treatment. At the moment of the transplantation, a posterior allogenic femoral condyle was prepared by free-hand technique ([Fig. 2]).
Fig. 2 Fresh osteochondral allograft from the posterior femoral condyle.
Immediately before the fixation of the transplant, a pulse lavage technique was used to remove cadaveric bone marrow elements to decrease the risk of local allogenic reaction. The Locking Compression Plate (LCP, DePuy Synthes, West Chester, PA, United States) was used for allograft fixation, as well as three small-fragment cortical screws for rotational control. A postoperative CT scan confirmed the anatomical position of the allograft and articular congruence ([Fig. 3]).
Fig. 3 Anatomical reduction confirmed through a postoperative computed tomography scan. The white arrow indicates the osteochondral allograft.
The postoperative protocol involved six weeks with no weight-bearing and no restriction regarding the range of motion. After six weeks, partial weight-bearing was allowed until twelve weeks of follow-up, with the radiological confirmation of complete bone healing. At two years of follow-up, radiologic assessment confirmed complete allograft integration and anatomical reduction ([Fig. 4 A-B]). No inflammatory reaction or local allogenic rejection was reported during the follow-up. The patient is now on a waitlist to complete the ligament-reconstruction approach regarding his complex knee injury.
Fig. 4 (A) Postoperative lateral view. (B) Postoperative anterior view.
Discussion
Hoffa fractures are typically related to motor-vehicle accidents and falls, depending on the angle of the knee at the moment of the trauma.[1] The patient described was involved in a high-energy trauma accident and suffered multiple fractures. Complete bone healing of femoral head, calcaneus, and posterior condyle fractures were confirmed at the last follow-up.
No surgical approach to HF is often associated with loss of joint mobility, yearly post-traumatic OA and limb malalignment. In the case of simple fractures, anterior-to-posterior fixation using the lateral or medial parapatellar approach represents a reasonable option.[1] Complex medial HF is usually addressed with a medial subvastus approach, while the Swashbucker approach or Gerdy tubercle osteotomy are suggested for complex HF at the LFC.[5] In the case reported, a medial subvastus interval was used, and the medial gastrocnemius was partially released from the MFC.
Unusual associations have been reported regarding HF and injury to the knee extensor mechanism, tibial-plateau fracture, tibial-spine avulsion, patella dislocation, and femoral-shaft fracture.[6] An additional CT scan is recommended for patients with suspected HF, while a magnetic resonance imaging (MRI) scan can be helpful to identify leasion to ligaments or the menisci.[5]
The case reported in this manuscript was associated with a complex knee ligament injury. At the time of the present report, we could not complete the reconstruction of the knee ligament to obtain a final functional result. Our group understands that, in the case of OCA transplantation, complete bone integration and healing should be achieved before the arthroscopic reconstruction of the knee. A similar case involving medial HF and multiple ligament injuries was previously reported after a motorcycle accident.[7] Other authors[8] have reported cases of HF and associated lesion to the attachment of the tibial meniscus, cruciate ligaments, and lateral collateral ligament avulsion. Letenneur et al.[9] identified the relationship between HF at the LFC and ACL tear or lateral collateral ligament injury. The association between HF and complex knee injury represents a challenging scenario, witch requires a comprehensive preoperative clinical and radiological diagnosis.
Transplantation of a large OCA has been considered as a reasonable approach after primary cartilage repair failure, post-traumatic OA, and failed fixation of previous articular fractures.[10] Concerns regarding the case reported involves the possibility of incomplete graft integration or chondral delamination, leading to transplant failure. However, it is also known that non-anatomical reduction and traumatic chondrocyte apoptosis result in secondary limb malalignment and early post-traumatic OA. To the best of our knowledge, the presented case is the first report of OCA transplantation after a complex HF.
Transplantation of the OCA resulted in complete bone healing and graft integration in the case reported. Restoration of the anatomical surface of the joint using fresh OCA should be considered in cases of complex HF to prevent early post-traumatic OA in young patients.
