Posttraumatic Reconstruction

Rationale for Primary TKA

ORIF of the tibial plateau is the mainstay of treatment in most operative cases of tibial plateau fractures. The goal of periarticular fracture fixation is to restore joint congruity and limb alignment using a stable fixation construct. Unfortunately, not all patients are ideal candidates for ORIF due to the presence of a complex fracture pattern and compromised healing related to their soft tissue and bone biology. Olderly patients with osteoporotic bone who suffer tibial plateau fractures can be considered potential candidates for an acute primary TKA as a definitive form of treatment for their injury.

Complications after ORIF of tibial plateau fractures have been shown to be higher in patients older than 60 years old. When considering ORIF in this patient population, the surgeon should be aware of the most common complications, including fixation failure, posttraumatic arthritis, nonunion, malunion, and medical complications related to a prolonged period of immobilization. In this patient population, the higher complication rate is believed to be due to more significant metaphyseal comminution, poor bone quality, and compromised soft-tissue envelope around the knee. In one retrospective study, a 79% fixation failure rate was documented in patients older than 60 compared with only 7% in younger patients. Additionally, the elderly have been shown to have a more difficult time adhering to weight-bearing precautions, which are crucial for success in the early weeks following ORIF. Poor compliance with weight-bearing restrictions has been shown to be an independent risk factor for fixation failure.

Indications and Benefits of Performing a Primary TKA

Primary TKA for a tibial plateau fracture has few indications and should only be undertaken in a specific patient population. Considering the complications associated with ORIF in this population, the elderly patient with preexisting knee osteoarthritis who is found to have a complex periarticular tibial plateau fracture in the setting of osteoporotic bone could be a candidate for definitive treatment with a primary TKA. Reconstruction with a TKA in this patient population treats both the fracture and concomitant knee osteoarthritis. The clinical finding of preexisting and symptomatic knee osteoarthritis is important in these patients as the absence of arthritis would favor a trial of nonoperative management versus ORIF. If the patient subsequently developed knee osteoarthritis, a TKA could then be considered at a later date.

Elderly patients with these fractures can often have medical comorbidities that would likely be exacerbated by prolonged immobilization after ORIF or can lead to the development of decubitus complications (e.g., pneumonia, deep vein thrombosis, decubitus ulcers). A clear benefit of performing a primary TKA is the ability to allow for immediate full weight bearing and knee range of motion without bracing. Similarly, select elderly polytrauma patients with other injuries that would preclude them from early mobilization (e.g., a contralateral lower limb fracture or an upper extremity fracture making use of assistive devices difficult) can also be considered for primary TKA.

Postoperative Outcomes Following Primary TKA

Postoperative outcomes after primary TKA for tibial plateau fractures are favorable in regard to functional scores. A recent systematic review of all studies performing primary TKA for tibial plateau fractures revealed excellent Knee Society Knee Scores and fair Knee Society Function Scores. ^, On average, in this systematic review, postoperative knee range of motion at midterm follow-up was found to be 108 ± 10 degrees. To date, there are no studies that directly compare outcomes of primary TKA versus ORIF for the treatment of tibial plateau fractures. Malviya et al. reported patient satisfaction of 90% and noted that 81% of patients returned to their premorbid functional status after primary TKA in their retrospective series of elderly patients. On average, these patients returned to ambulation without use of assistive devices by postoperative day 24.

In the literature, the complication rate averages 15% (range 0%–50%) in these primarily small and retrospective studies. In the largest case series in the literature (n = 30), a reoperation rate of 23% was described. Complications requiring reoperation included: wound complications, periprosthetic fracture, deep infection, removal of loose cement, and revision for aseptic loosening. At midterm follow-up, mortality rates averaged 4.8%.

These results suggest that primary TKA is a valid option for a select group of elderly patients with tibial plateau fractures. Patient selection is important, given the potential complications that this surgery holds. Additionally, it is recommended that a surgeon comfortable with revision arthroplasty techniques performs the reconstruction, given the complexity of the case, which is more similar to revision arthroplasty than a standard TKA for atraumatic osteoarthritis.

Surgical Approach and Decision-Making

As with any complex surgery, preoperative workup and planning are essential for a successful outcome. Examination of the affected extremity should be evaluated for skin and soft-tissue compromise, particularly in an elderly population that is more likely to have a friable soft-tissue envelope following acute trauma. Surgical timing depends on the soft-tissue envelope, but a significant delay is not required. In one study, TKA was performed within an average of 4 days from injury; only one postoperative wound complication was noted. A thorough preoperative medical evaluation must be undertaken to ensure that the patient is optimized to undergo a complex arthroplasty procedure.

Preoperative imaging should include plain radiographs and computed tomography (CT) of the injured knee for fracture pattern identification. Plain radiographs of the ipsilateral tibia and femur should be obtained to rule out any extraarticular deformity, as well as any proximal or distal hardware as the final arthroplasty components often require long stems. Consider obtaining plain radiographs of the contralateral knee to assist with preoperative templating.

Implant choice should be carefully considered well in advance of the operation. Generally, an implant system that creates a balanced knee restores the joint line, and provides knee stability with the least constraint possible should be selected, given concern for earlier aseptic failures with a higher level of constraint. Given that ligamentous injury has been reported to be as high as 71% after tibial plateau fractures, implants with various levels of constraint ought to be made available in the event of compromised collateral ligaments. Similarly, bone loss in these osteoporotic patients can create instability requiring a higher level of constraint such as a condylar constrained implant or even a rotating hinge implant for more significant bony defects. Restoration of bone defects with the use of cement, bone graft, tibial sleeves, or cones must be anticipated. A modular system with stemmed implants should be available as fractures that extend from the plateau into the metaphysis or diaphysis should be bypassed by at least two cortical diameters. Stems also offer the advantage of dispersed stress across the fractured tibia and should be considered with the use of more constrained implants. Additionally, fracture fragment trays, locking plates, and cerclage wires should be available to recreate a stable bony platform prior to the placement of arthroplasty components.

A standard midline incision is recommended. A medial parapatellar arthrotomy is generally sufficient for visualization; however, extensile exposures may be required. Hsu et al. recommend the following systematic approach when performing primary TKA for treatment of periarticular fractures around the knee. First, they recommend preventing fracture propagation using cerclage wires around any fractures that extend into the metadiaphyseal region. Cerclage wires will facilitate the use of intramedullary guides to minimize the risk of fracture propagation or displacement. Next, any fractures of the medial and lateral plateaus are reduced and temporarily fixed with K-wires. Standard fracture fixation principles are followed with the use of plates and/or screws to reconstruct the normal plateau anatomy or to unite any metadiaphyseal fracture fragments.

Following fracture stabilization, attention is turned to reconstruction of the tibial platform. Intramedullary guides are used to make a bone preserving proximal tibia cut. Any bone defects are noted and fill of contained or uncontained defects can be planned with the above-mentioned techniques. If a tibial stem is required, intramedullary preparation is performed. Attention can then be turned to femoral preparation. According to standard knee arthroplasty principles, care must be taken to recreate the joint line and posterior condylar offset in order to optimize knee kinematics.

At this point, the level of implant constraint is selected based on the integrity of the collateral ligaments and the bony architecture. Our most commonly employed implant in this patient population is a semi-constrained knee with stems that bypass the fracture site. However, there is no consensus in the literature regarding the level of constraint required for these cases; these case series with favorable outcomes range from the use of posterior stabilized implants up to rotating hinge systems. Following the placement of trial components, knee kinematics are assessed, and joint stability is verified prior to final component placement. Standard cement techniques are used for implant placement. With a stable construct and well-stabilized knee, the patient is allowed to bear weight as tolerated and fully range the knee without use of a brace.