Outcomes after the dome high tibial osteotomy from 1-20 year follow-up.
The objectives of this study are to report outcomes data and survivorship of dome high tibial osteotomy (HTO) with follow-up from 1-20 years.
An IRB approved retrospective review of data was performed for patients who underwent dome HTO from a single surgeon between April 1983 and June 2003. Patients were included who underwent a dome HTO for varus alignment and had >1 year follow-up data. A modified HSS knee score was analyzed with average latest outcome score with standard deviations reported. A Kaplan-Meier survivorship was performed for both outcomes score threshold and for conversion to total knee arthroplasty (TKA). Radiographic measurements were obtained.
147 knees (134 patients) were included in the study. There were 95 (69%) males and 42 (31%) females. There were 75 (51%) right knees and 72 (49%) left knees. The mean length of follow-up was 9 +/- 5 years (Range = 1-20 years). The mean age at the time of surgery was 56 +/- 9 year (Range = 28-75 years) and at the latest follow-up was 66 +/- 9 years (Range = 44-85 years). Average modified HSS knee score improved from 62.0 pre-operatively to 85.7 post-operatively.
Kaplan-Meier curve of the total 147 knees in the study, for a modified HSS knee score >85 as endpoint showed survival rate was 70% at 5 years, 56% at 10 years, 47% at 15 years, 37% at 17 years. The average survival time was 12 years and 67 knees reached endpoint >85 on the modified HSS knee score during the study. Kaplan-Meier curve of the 150 knees for TKA survivorship (147 knees in the study + 3 knees with TKA data but not in overall analyses), showed a survival rate of 93% at 5 years, 76% at 10 years, 63% at 15 years, 44% at 19 years. The average survival time was 16 years.
Analyzing the 147 knees in the study, mechanical axis deviation (MAD) as measured by a percent hemitibia versus femoral tibial angle (FTA) is a linear relationship. A scatter plot shows excellent correlation between MAD by FTA for each pair that was available. There were a total of 619 MAD/FTA x-ray pairs, where a pair is from the same x-ray exam date.
Complications reported included 24 infections (16%), 6 patients with peroneal neuropraxia (4%), 5 with delayed union (3%), 4 with non-union (3%), 4 with over-correction (3%), 2 patient with phlebitis (1%).
This retrospect review of 147 dome HTO patients with 1-20 year follow-up shows that outcomes scores significantly improved at final follow-up compared to pre-operative scores. The survivorship of outcomes >85 points on the modified HSS knee score after dome HTO averaged 12 years with 67 knees maintaining this outcome score at final follow-up. The survivorship of knees undergoing dome HTO with endpoint of TKA averaged 16 years with 44% avoiding arthroplasty at 19 years post-operative. Radiographic analysis shows that MAD and FTA have a linear relationship and can be used interchangeably to determine correction.