Closing Wedge High Tibial Osteotomy for Medial Compartment Osteoarthritis

John F. Rudan, M.D., FRCSC
Kingston, ON

High tibial osteotomy is an effective treatment for mild to moderate medial compartment osteoarthritis of the knee in physiologically young and active people. Good to excellent clinical results are reported in over 90% of patients for over ten years1.

The major pitfalls associated with failures are most frequently related to two factors. Firstly, overextending the indications for surgery to patients with severe medial compartment plus or minus severe symptomatic patello-femoral disease is associated with earlier clinical failure. The second causal factor of failure is due to over or under correction of femoral-tibial alignment. The most common problem is an anatomic axis correction to less than seven degrees of valgus or over correction of the anatomic axis with alignment greater than 12 of valgus.


Planning appropriate correction is important. Three foot standing X-rays are essential with a ruler to determine magnification error. Be aware that approximately four degrees of additional correction, beyond the correction calculated from the removal of bone, occurs in patients with a femoral shaft-transcondylar angle of greater than 10 valgus. As a result, these patients are prone to excessive valgus over-correction2.

Through a midline anterior skin incision, I expose the proximal tibia laterally reflecting the anterior compartment muscles to expose the proximal tibial-fibular joint. Care is taken not to dissect below the inferior capsule. This protects the peronel nerve. Using the image intensifier, I place guide pins parallel to the tibial articular surface at least one centimetre from the articular surface. From my calculations, I measure the absolute distance of the lateral cortex to be removed for the desired angle of correction. Measurement of the distance is calculated from the standing X-rays with compensation for magnification. A second k-wire is inserted using the image intensifier control so as to mark the desired lateral cortical bone resection. The lower k-wire is placed such that the osteotomy will be above the tibial tubercle. Resection using an oscicllating saw is performed between the k-wires. Care is taken to cut the distal and proximal planes parallel to each other in the sagittal plane to prevent loss of posterior slope tibia of the tibia. The osteotomy is completed by osteoclasis. The correction is reviewed under image intensification. Should the osteotomy open medially, a staple is placed medially in order to maintain closure of the osteotomy. Two staples are placed laterally and images are used to check that the staples do not penetrate the knee joint.

No casting is needed, full range of motion and weight bearing is tolerated and is started immediately postoperatively. Recently, we have been performing the osteotomy using computer-assisted techniques to improve osteotomy accuracy. Results using this technology have shown a statistically significant improvement in angular corrections.


References

  1. Simurda, M., Rudan, J. (1991) Valgus High Tibial Osteotomy: A Long Term Follow-up Study. Clinical Orthopaedics and Related Research. Vol. 268, 157-60.
  2. Simurda, M., Harrison, M., Rudan, J. (1998) Optimizing Femoral Tibial Alignment in High Tibial Osteotomy Canadian Journal of Surgery, 41: 398-402

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