Unicompartmental Knee Arthritis: High Tibial Osteotomy

Thomas Turgeon, M.D., FRCSC
Assistant Professor, University of Manitoba
Winnipeg, MB

High tibial osteotomy (HTO) has been a long-standing treatment for osteoarthritis of the medial compartment of the knee. In recent decades, advances in arthroplasty have shifted the focus of knee arthritis procedures away from joint preserving osteotomies. Despite this trend, HTO continues to play an important role in the treatment of appropriately selected patients.

The underlying premise of the HTO is that by changing the alignment at the knee, the load-bearing axis of the limb can be shifted away from the diseased medial compartment. More of the force is then borne by healthy lateral structures relieving pain. This premise relies on the relative varus knee alignment associated with medial osteoarthritis resulting in a mechanical axis which preferentially loads the damaged portion of the joint.

There are a variety of surgical techniques described for HTO. The lateral closing wedge osteotomy does reliably provide angular correction and fixation; however, concerns have been raised about the risk of injury to the peroneal nerve. The medial opening wedge osteotomy has been gaining popularity in recent years. The combination of a single bone cut with the ability to adjust the correction intra-operatively is attractive to surgeons. Fixed-angle fixation devices and advances in bone graft substitute have also increased the use of this technique. A randomized trial found a higher rate of symptomatic hardware removal and less accurate angular correction with opening wedge HTO, but no difference in clinical scores3. A recent cohort study found that opening wedge HTO with a non-locking plate had a significantly higher rate of early complication and loss of correction as compared to a closing wedge techniques14. Fixed-angle devices have been promoted to potentially improve the accuracy of opening wedge procedures. Hemicallotaxis procedures with the use of ring external fixators have also been suggested. These techniques have high rates of bony union, combined with better accuracy and maintenance of correction. External fixators do continue to be plagued by pin-track complications and patient inconvenience7,8. Dome-shaped osteomies have also been used. They provide greater potential for large corrections, but can be technically challenging to perform.

Selection of appropriate candidates for surgery is vital to success. Patients should have a well-preserved lateral knee compartment and relative varus alignment. Traditionally, ligamentous instability was considered a contra-indication; however, HTO is now coupled with soft-tissue and cartilage procedures to address such issues. Recent studies have shown that younger patients are more likely to have lasting success. Flecher, et al. found that subjects over the age of 50 had higher rates of conversion to arthroplasty while Trieb, et al. found that each year of increased age at surgery was associated with a 7.6% increased hazard of failure4,13. Not surprisingly, these studies also found that subjects with advanced arthritis did not benefit as much as subjects with lesser disease severity. Patients who expect to return to high physical demands that would exceed the limits of arthroplasty components can also be considered for HTO. Ideal candidates are relatively young, active individuals with mild to moderate osteoarthritis isolated to the medial compartment of a varus knee.

Degree of correction has also been debated. Cadaveric studies have suggested that as much as 25 degrees of correction would be required to effectively offload the medial compartment2,10. Despite this, good results are reported with a final alignment of eight to 16 degrees of valgus1,11. Correction below or above this amount are associated with higher rates of failure.11

While successful in the majority, HTO results do decline with time. Several recent long-term studies have found 74% to 80% survival at ten years dropping to 57% to 67% by 15 years1,9,11,12. Survival was found to increase to 90% at ten years among the subset of patients with a correction of eight to 16 degrees of valgus after complete bony union11. Previous treatment with HTO does complicate future arthroplasty options. Conversion to total knee arrthroplasty has been shown to be technically more challenging with longer surgical times and radiographic changes such as patellar height and implant impingement on the tibial cortex. A matched study of primary knee arthroplasty and post-HTO knee arthroplasty found no functional difference at a mean of 4.5 years6. In contrast, longer follow-up of subjects to a mean of 12.5 years found reduced flexion and higher rates of re-operation in patients with prior HTO5. The failures in this study tended to occur late in the follow-up period.

HTO continues to be a valuable treatment option for selected patients with isolated medial knee osteoarthritis. Good results can be expected for most patients out to ten years with subsequent decline thereafter. Later conversion of HTO to knee arthroplasty is technically more challenging and may not achieve the same degree of success as primary knee arthroplasty, but this finding must be compared to the alternative of early arthroplasty with potential revision within a similar time frame.

References

  1. Aglietti, P.; Buzzi, R.; Vena, L. M.; Baldini, A.; and Mondaini, A.: High tibial valgus osteotomy for medial gonarthrosis: a 10- to 21-year study. J Knee Surg, 16(1): 21-6, 2003.
  2. Agneskirchner, J. D.; Hurschler, C.; Wrann, C. D.; and Lobenhoffer, P.: The effects of valgus medial opening wedge high tibial osteotomy on articular cartilage pressure of the knee: a biomechanical study. Arthroscopy, 23(8): 852-61, 2007.
  3. Brouwer, R. W.; Bierma-Zeinstra, S. M.; van Raaij, T. M.; and Verhaar, J. A.: Osteotomy for medial compartment arthritis of the knee using a closing wedge or an opening wedge controlled by a Puddu plate. A one-year randomised, controlled study. J Bone Joint Surg Br, 88(11): 1454-9, 2006.
  4. Flecher, X.; Parratte, S.; Aubaniac, J. M.; and Argenson, J. N.: A 12-28-year followup study of closing wedge high tibial osteotomy. Clin Orthop Relat Res, 452: 91-6, 2006.
  5. Haslam, P.; Armstrong, M.; Geutjens, G.; and Wilton, T. J.: Total knee arthroplasty after failed high tibial osteotomy long-term follow-up of matched groups. J Arthroplasty, 22(2): 245-50, 2007.
  6. Kazakos, K. J.; Chatzipapas, C.; Verettas, D.; Galanis, V.; Xarchas, K. C.; and Psillakis, I.: Mid-term results of total knee arthroplasty after high tibial osteotomy. Arch Orthop Trauma Surg, 128(2): 167-73, 2008.
  7. Magyar, G.; Ahl, T. L.; Vibe, P.; Toksvig-Larsen, S.; and Lindstrand, A.: Open-wedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of 50 operations. J Bone Joint Surg Br, 81(3): 444-8, 1999.
  8. Magyar, G.; Toksvig-Larsen, S.; and Lindstrand, A.: Changes in osseous correction after proximal tibial osteotomy: radiostereometry of closed- and open-wedge osteotomy in 33 patients. Acta Orthop Scand, 70(5): 473-7, 1999.
  9. Papachristou, G.; Plessas, S.; Sourlas, J.; Levidiotis, C.; Chronopoulos, E.; and Papachristou, C.: Deterioration of long-term results following high tibial osteotomy in patients under 60 years of age. Int Orthop, 30(5): 403-8, 2006.
  10. Shaw, J. A., and Moulton, M. J.: High tibial osteotomy: an operation based on a spurious mechanical concept. A theoretic treatise. Am J Orthop, 25(6): 429-36, 1996.
  11. Sprenger, T. R., and Doerzbacher, J. F.: Tibial osteotomy for the treatment of varus gonarthrosis. Survival and failure analysis to twenty-two years. J Bone Joint Surg Am, 85-A(3): 469-74, 2003.
  12. Tang, W. C., and Henderson, I. J.: High tibial osteotomy: long term survival analysis and patients' perspective. Knee, 12(6): 410-3, 2005.
  13. Trieb, K.; Grohs, J.; Hanslik-Schnabel, B.; Stulnig, T.; Panotopoulos, J.; and Wanivenhaus, A.: Age predicts outcome of high-tibial osteotomy. Knee Surg Sports Traumatol Arthrosc, 14(2): 149-52, 2006.
  14. van den Bekerom, M. P.; Patt, T. W.; Kleinhout, M. Y.; van der Vis, H. M.; and Albers, G. H.: Early complications after high tibial osteotomy: a comparison of two techniques. J Knee Surg, 21(1): 68-74, 2008.

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