High tibial osteotomy has proved successful in treating unicompartmental arthritis in young, active patients.1-3 However, this procedure fails over time because the other compartments deteriorate.4 The next step is conversion of the osteotomy to total knee arthroplasty (TKA). Conversion results vary, with several authors reporting poor outcomes5-9 and others reporting outcomes equal to those of primary TKA.10-14
The long-term success of TKA depends on proper restoration of the mechanical axis and soft-tissue balancing.15 Preexisting extra-articular deformity may adversely affect outcomes. A deformity of more than 15° may make it difficult to obtain intra-articular correction of an extra-articular deformity through soft-tissue balancing alone.16
In this article, we report the unique case of a patient whose bilateral high tibial osteotomies failed because of excessive extra-articular deformity. TKAs were performed consecutively, in 2 separate settings. Each TKA was combined with a recorrection tibial osteotomy in a single operation, allowing for re-creation of normal knee alignment with ligament balance. The patient provided written informed consent for print and electronic publication of this case report.
Case Report
A 58-year-old man (weight, 250 pounds; body mass index, 30) underwent staged bilateral medial opening wedge osteotomies using distraction osteogenesis. A uniplanar external fixator was used for fixation on each knee. Before surgery, anatomical axis was 2° (right knee) and –1° (left knee) (Figure 1A), and tibial slope was 9° (right) and 8° (left) (Figures 1B, 1C). The procedures were performed 10 months apart. After surgery, anatomical alignment was 17° valgus (right knee) and 12° valgus (left knee) (Figure 2), and tibial slope was 20° (right) and 13° (left).
The patient received mild relief of his arthritis symptoms. Fifty-six months after the index operation, he decided to undergo conversion of the right high tibial osteotomy to TKA because of progressive painful arthritis of the knee. Excessive valgus alignment caused by the initial osteotomy raised concerns about being able to correct the extra-articular deformity intra-articularly while maintaining kinematic ligament balance. For this reason, a recorrection osteotomy was performed concurrently with the TKA. A posterior cruciate ligament–retaining (PCL-retaining) knee design (NexGen, Zimmer) was selected.
The procedure began with bone cuts for the TKA. Initial cuts were made on the femur. The tibial cut was made in valgus corresponding to the preoperative valgus deformity. The tibial recorrection osteotomy was made at the level of the original osteotomy site. A stemmed tibial component was used to cross the osteotomy site, correcting the valgus deformity and providing stability at the osteotomy site. A 3.5-mm locking compression T-plate (Synthes) was medially placed to prevent loss of correction and control rotation of the osteotomy during healing. The patient began range of motion on postoperative day 1. Continuous passive motion was not used. Protective weight-bearing continued for 6 weeks. After 6 weeks, and once there was radiograph evidence of healing at the osteotomy site, full weight-bearing was allowed.
After 4 months, the patient decided to undergo a similar procedure on the left knee. Postoperative rehabilitation was the same. A year after the bilateral TKAs, the patient maintained a Knee Society Score of 95 and a functional score of 90. After surgery, anatomical alignment was 6° (right knee) and 3° (left knee) (Figure 3), and tibial slope was 6° (right) and 7° (left) (Figures 4A, 4B). In each knee, the PCL was preserved with ligament balance.
Discussion
Clinical outcomes of TKA after high tibial osteotomy vary. Windsor and colleagues9 reported that knee arthroplasties after tibial osteotomy were less successful than primary TKAs. In small studies, both Staeheli and colleagues17 and Katz and colleagues5 found that TKA outcomes after osteotomy were satisfactory compared with outcomes of primary TKA without previous osteotomy. A meta-analysis by Ramappa and colleagues18 showed no difference in outcomes between TKAs with and without previous osteotomy. In addition, there were no differences in outcomes between TKAs performed after opening wedge versus closing wedge osteotomies.19
An arthritic knee compartment is unloaded when a high tibial osteotomy produces an extra-articular deformity. Neyret and colleagues7 reported difficulties in correcting angulations of 9° or more through soft-tissue release. Cameron and Welsh16 suggested pre–knee arthroplasty correction of the extra-articular deformity for malalignments of more than 15°. In cases of severe malalignment produced by an osteotomy, Katz and colleagues5 also suggested that a second osteotomy be performed to correct alignment before TKA.
For TKA after high tibial osteotomy, a neutral plateau resection removes more bone medially than laterally, creating medial laxity. Without correction of the tibial deformity, lateral release (or, as Krackow and Holtgrewe20 advocated, medial advancement) is required for ligament stability. Both technically demanding options may not provide complete stability throughout the arc of motion. In addition, neither corrects for rotational or sagittal deformities (the concern with correcting an extra-articular deformity with intra-articular ligament balancing).