Intraoperative tibial plateau fracture during bone preparation in a cruciate retaining primary total knee arthroplasty

Background

Intraoperative fractures during primary total knee arthroplasty (TKA) are a rare complication, with a reported incidence of 0.4%–2.2%.1–4 The tibia is less commonly fractured when compared with the femur, however the incidence is rising due to increase in total number of TKAs annually.1 5 6 Non-surgical risk factors that increase the risk of these fractures are female sex, osteoporosis and steroid abuse.1 2 4 Surgical risk factors include long tibial stems, posterior-stabilised designs, revision surgery, implant malposition and forceful impaction of trial implants.4 5 7 Although intraoperative fractures can occur at any point during the TKA, they commonly occur during bone exposure and preparation as well as during placement of final components.1 2

Literature regarding management of intraoperative fractures during primary TKA remains limited.2 In 2015, Ebraheim et al performed a systematic review of periprosthetic tibia fractures and their treatment using the classification developed by Felix in 1997.8 9 Treatment modalities include non-operative management, plate and screw fixation, stemmed prosthesis and screw fixation.1 3 10 11 The goal of managing these fractures is to create a construct that resists axial, rotational and sheer forces on the final components.2

We present a unique case of an 80-year-old man who sustained an intraoperative medial tibial plateau fracture during final tibial bone preparation using the Woolley Tibia Punch (Innomed, Savannah, Georgia, USA).

Case presentation

An 80-year-old man presented to the orthopaedic clinic with chronic right knee pain that had been progressing over multiple years. Management options prior to presentation included the utilisation of non-steroidal anti-inflammatory drugs, physical therapy and corticosteroid injections. These modalities provided initial relief with diminishing effect over the years. His medical history included hyperlipidaemia, hypertension, prostate cancer. The patient’s prostate cancer was treated years prior with radiation therapy alone and the patient was in remission. His surgical history was significant for a left TKA 15 years prior to presentation with excellent outcome. Physical examination of the right knee revealed a body mass index of 37 kg/m², genu varum with tenderness to palpation of the medial and lateral joint lines. Range of motion was 5° of extension to 95° of flexion. No other musculoskeletal abnormalities were observed on both the knee and hip examinations, and the patient was neurovascularly intact. Weight-bearing anteroposterior, lateral and sunrise radiographs of the right knee were obtained and showed Kellegran-Lawrence grade 4 osteoarthritis with no evidence of acute fractures (figure 1).

After a thorough discussion of the risks and benefits of primary TKA, the patient elected to proceed with surgical intervention. Preoperative labs, ECG and chest radiographs showed no abnormalities and the patient was scheduled for elective TKA. Preoperative considerations unique to this patient’s case included the significant varus deformity present. The possible need for a stepped tibial cut with a stemmed implant was discussed with the patient.

Treatment

On the day of surgery, the planned procedure was confirmed with the patient in the preoperative area. The patient was brought back to the operating room and placed in the supine position. General anaesthesia was then induced. The right knee was prepped and draped in the usual sterile fashion and a preoperative time out was performed with all members of the surgical team. A standard, midline incision with medial parapatellar arthrotomy was made. This was followed by sequential exposure and preparation of the distal femur and proximal tibia using the Smith and Nephew OrthoAlign handheld navigation system. It was determined intraoperatively that a stepped cut of the tibia was not necessary, as standard polyethylene inserts would sufficiently replace the necessary amount of resection. A straight flat cut was made on the tibia with 12 mm removed off the lateral tibia and 1 mm off the medial tibia. Trialling was performed and all gaps were appropriately balanced. Implants were then obtained, and final preparation of the distal femur and proximal tibia took place during cement preparation.

Given the degree of preoperative varus deformity and minimal medial tibial resection, the medial tibial plateau remained sclerotic following final bone cuts. In order to maximise cement interdigitation during final component placement, the medial tibial plateau was further prepared using a Woolley Tibia Punch (figure 2). Use of the Woolley Tibia Punch to increase bone/cement interface in sclerotic bone secondary to deformity is an advertised use of the device. Use of the device resulted in fracture of the medial tibial plateau, as demonstrated by direct visual confirmation and intraoperative fluoroscopy (figure 3).

Management of this intraoperative complication consisted of operative fixation of the fracture followed by conversion to a long-stemmed implant. As one batch of cement was in the process of being mixed, the patellar component was placed prior to addressing the intraoperative fracture. Attention was then turned to the medial tibial plateau fracture.

Reduction was achieved with the use of pointed reduction clamps and confirmed using direct visualisation in addition to intraoperative fluoroscopy. Operative fixation was achieved with the use of two 4.5 mm cortical lag screws and washers. Care was taken during placement of these lag screws to avoid the trajectory of the final implant. A keel trial was placed within the tibia during screw placement in order to ensure avoidance (figure 4). Intraoperative fluoroscopy was used to confirm anatomic reduction and appropriate placement of hardware (figure 5). A stem was then added to our tibial component (100×14 mm extension) in order to bypass the fracture site and rely on diaphyseal engagement. The tibial canal was then sounded to accommodate the stem, and final components were cemented in place (figure 6).

After again checking range of motion, patellar tracking and gap balance, the wound was thoroughly irrigated and closed. The patient was extubated and left the operating room without complication.

Outcome and follow-up

The patient was discharged and instructed to remain partial weight-bearing in the right lower extremity for 6 weeks. Partial weight-bearing for this patient was defined as allowing the weight of the leg to rest on the floor however not passing full body weight through the leg during ambulation. The patient used a combination of crutches and walker for a total of 6 weeks to assist in this form of weight-bearing. At 6 weeks follow-up, radiographs confirmed maintenance of hardware and implant alignment (figure 7). Additionally, the patient was pain free and tolerating range of motion 0°–100°. His weight-bearing was advanced to full weight-bearing at that time.