Abstract
Background:
Total hip arthroplasty (THA) has been proven to be successful in achieving adequate pain relief and favorable outcomes in patients suffering from hip osteoarthritis (OA). However, leg length discrepancy (LLD) is still a significant cause of morbidities such as nerve damage, low back pain and abnormal gait. Despite most of the reported values of LLD in the literature being within the acceptable threshold of < 10 mm, some patients still report dissatisfaction, leading to litigation against orthopedic surgeons. However, lower extremity lengthening is sometimes necessary to achieve adequate hip joint stability and prevent dislocations. The purpose of this study was to compare LLD in patients undergoing THA using three different techniques: conventional anterior-approach THA (ATHA), conventional posterior-approach THA (PTHA), and robotic-assisted posterior-approach THA (RTHA) using the MAKO™ robotic hip system.
Materials and Methods:
All cases of RTHA, ATHA and PTHA that were performed by the senior surgeon between Sep 2008 and Dec 2012 were reviewed. Patients included in this study had a primary diagnosis of hip osteoarthritis, with available and proper post-operative antero-posterior pelvis radiographs. All radiographs were calibrated and measurements done twice by two blinded observers.
Results:
After exclusions, 67 RTHA cases, 29 ATHA cases and 59 PTHA cases were included in this study. There was a strong inter- and intra-observer correlation for all LLD measurements (r > 0.9, p < 0.001 in all). Mean LLD in the RTHA, ATHA and PTHA groups was 2.7 ± 1.8 mm (CI95: 2.3, 3.2), 1.8 ± 1.6 mm (CI95: 1.2, 2.4) and 1.9 ± 1.6 mm (CI95: 1.5, 2.4) respectively (p = 0.01). When LLD > 3 mm was set as an outlier, the percentage of patients in the RTHA, ATHA and PTHA groups was 37.3%, 17.2% and 22% respectively (p value range, 0.06–0.78). When LLD > 5 mm was set as an outlier, the percentage of patients in the RTHA, ATHA and PTHA groups was 10.4%, 6.9% and 8.5% respectively (p value range, 0.72–1.0). None of the patients in all three groups had LLD ≥ 10 mm (Figure 1).
Conclusion:
The results of the current study demonstrate the accuracy of the MAKO™ system in obtaining minimal LLD compared to the conventional anterior-approach and conventional posterior-approach THA, with no cases having LLD > 10 mm.
