Commentary on
"Proximal Tibial Varus Osteotomy. Indications, Technique
and Five to Twenty-three Year Results",
by René K. Marti et al.

Commentary by Daniel J. Berry, MD,
Mayo Clinic, Rochester, MN 55905

In the February 2001 issue of JBJS-A, Marti and coworkers present the long-term results of opening wedge proximal tibial osteotomy for the treatment of lateral compartment osteoarthritis of the knee. The operation was performed on 36 patients over a period of 19 years (1974 to 1993) and 34 patients were followed for five to twenty-three years. Only one patient subsequently had another reconstructive knee operation and none of the remaining patients had marked progression of their osteoarthritis. The clinical subjective results were rated as excellent in 9 patients, good in 21, fair in 3 and poor in 1 of 34 patients at a mean follow-up of eleven years.

Angulation osteotomies of the tibia and femur have a well-established record as safe and effective treatments for osteoarthritis of the knee that is confined primarily to the medial or lateral compartment. Angulation osteotomies have been performed less frequently in recent years as total knee arthroplasty has assumed a broader role in the treatment of knee arthritis. Total knee arthroplasty provides the advantages of predictable pain relief and good clinical function, and because the planning and execution of total knee arthroplasty is relatively straightforward, orthopaedic surgeons may feel more comfortable performing that procedure rather than osteotomy. Nevertheless, angulation osteotomy remains the procedure of choice for many young and active patients with unicompartmental osteoarthritis of the knee, particularly when it occurs in association with an angular deformity.

Most of the literature on angulation osteotomy about the knee has focused on valgus-producing upper tibial osteotomy to treat medial compartment gonarthrosis, and there is less information on angulation osteotomy for the treatment of lateral compartment arthritis. Lateral compartment osteoarthritis most commonly occurs in association with a hypoplastic lateral femoral condyle. This anatomic problem leads to valgus knee angulation with a joint line that slopes from proximal-lateral to distal-medial. Varus-producing osteotomies designed to correct limb alignment under these circumstances usually are performed at the supracondylar level of the femur which minimizes the ultimate joint line obliquity and thus theoretically reduces shear stresses on the cartilage. Indeed, a number of authors have reported successful results for supracondylar femoral osteotomy for the treatment of lateral compartment disease^1-3. However, there is a subpopulation of patients with a valgus knee deformity that, for a variety of reasons, most commonly due to a post-traumatic deformity, have a primarily tibial deformity. For these patients, the twin goals of angular correction and minimization of the joint line obliquity can be achieved with a proximal varus-producing tibial osteotomy. This subpopulation of patients forms the cohort for the report by Marti et al. The authors used the operation selectively, and it is notable that during the time period covered by this study they performed more than three times as many supracondylar femoral osteotomies as proximal tibial varus osteotomies for the treatment of lateral compartment gonarthrosis.

Many different osteotomies-including opening and closing-wedge osteotomies and dome-shaped osteotomies-fixed with a variety of methods (staples, standard plates, special plates, and external fixation) can be used to produce a varus correction of the proximal tibia. Percutaneous osteotomies with distraction osteogenesis and external fixation also have been used. In the classic article on the subject of varus-producing proximal tibial osteotomies, Coventry⁴ reported favorable results for a medial wedge closing proximal tibial osteotomy performed above the tibial tubercle. He believed that the operation was indicated if the valgus deformity was less than 12° and the joint line resulting from the osteotomy would slope less than 10°. The technique described by Marti et al. is a lateral opening-wedge osteotomy performed above the level of the tibial tubercle. Autogenous corticocancellous iliac crest graft was used in all patients. Advantages of this technique include: (1) the ability of the surgeon to adjust correction as needed after the osteotomy is made, (2) the production of little proximal tibial deformity (and thus a less negative impact on future knee arthroplasty), and (3) avoidance of internal fixation devices on or near the pes tendons. Disadvantages include: (1) the donor site morbidity associated with tricortical iliac crest harvest, (2) the slight movement of the patella to a distal position relative to the joint line, and (3) the risk of peroneal neuropathy because of acute stretching of the peroneal nerve. In the series by Marti et al., the rate of peroneal neuropathy was 9%, and although all recovered within a year, the risk of this complication deserves emphasis. Even though it is generally accepted that an opening-wedge osteotomy carries a greater risk of nonunion than does a closing-wedge osteotomy, the authors had none in this series; a variety of combinations of internal fixation and external immobilization were used to achieve this success.

Good results from angulation osteotomies about the knee are critically dependent upon optimal patient selection and exacting operative technique⁵. The mean age of patients in this series was 43 years and none was older than 66. Most had post-traumatic, post-lateral meniscectomy or post-osteotomy-related deformities. Not stated in the paper are some other patient characteristics that may also play an important role in determining suitability as an osteotomy candidate, including body mass index, major medical co-morbidities, and the radiographic status of the medial and patellofemoral compartments. Subtleties in patient selection probably contributed to the high success rate of the procedure in this report. The authors rightly emphasize the importance of careful preoperative planning and intraoperative assessment in achieving overall optimal alignment of the limb. Reliable correction of the axis to within the desired range correlates strongly with the outcome of all osteotomies around the knee and undoubtedly also had a positive impact on the results in this report⁵.

In summary, this excellent paper provides convincing evidence that opening-wedge proximal tibial osteotomy can provide very good results at mid and long term in selected patients with a valgus knee deformity and lateral compartment osteoarthritis. The authors provide valuable information on the technique that they have used to achieve reliable and lasting success with the operation.

1. Edgerton BC, Mariani EM, Morrey BF. Distal femoral varus osteotomy for painful genu valgum. A five- to eleven-year follow-up study. Clin Orthop. 1993;288:263-9.

2. Healy WL, Anglen JO, Wasilewski SA, Krackow KA. Distal femoral varus osteotomy. J Bone Joint Surg Am. 1988;70:102-9.

3. McDermott AG, Finkelstein JA, Farine I, Boynton EL, MacIntosh DL, Gross A. Distal femoral varus osteotomy for valgus deformity of the knee. J Bone Joint Surg Am. 1988;70:110-6.

4. Coventry MB. Proximal tibial varus osteotomy for osteoarthritis of the lateral compartment of the knee. J Bone Joint Surg Am. 1987;69:32-8.

5. Coventry MB, Ilstrup DM, Wallrichs SL. Proximal tibial osteotomy. A critical long-term study of eighty-seven cases. J Bone Joint Surg Am. 1993;75:196-201.