Changes of the coronal lumbar-pelvic-femoral alignment after conversion total hip arthroplasty in patients with unilateral ankylosed hip

Radiographic factors affecting contralateral knee alignment in patients with dysplastic hip osteoarthritis

INTRODUCTION

Patients with dysplastic hip arthritis (DHA) often present with abnormal knee alignment. We investigate the factors influencing varus and valgus knee alignment on the contralateral side in patients with unilateral DHA.

METHODS

123 patients with unilateral DHA were enrolled between 2018 and 2022. Based on the hip-knee-ankle angle (HKAA), patients were divided into three groups: neutral group (HKAA <3° varus and valgus), varus group (>3° varus), and valgus group (>3° valgus). Demographics, radiographic parameters, and functional scores were compared between the groups.

RESULTS

There were 58, 44, and 21 patients in the neutral, varus, and valgus group, respectively. The varus group had a varus HKAA and hip adduction angle in the affected hip and a large femoral offset in the healthy hip. The valgus group had a valgus HKAA and large hip adduction angle in the affected hip and a small femoral offset in the healthy hip. In addition, the valgus group presented with pelvic obliquity, expressed as an upper pelvic tilt on the affected side. Multivariate analysis identified a varus HKAA in the affected hip (odds ratio [OR], 0.64; 95% confidence interval [CI]: 0.51-0.79; p < 0.01) as a factor associated with the varus group, while pelvic obliquity (OR, 0.69; 95% CI: 0.53-0.89; p = 0.01) was associated with the valgus group. The varus and valgus groups had significantly worse functional scores than the neutral group.

CONCLUSIONS

This study demonstrated that varus and valgus alignments of the contralateral knee with unilateral DHA were associated with radiographic parameters and hip function.

Characteristics of pelvic obliquity in dysplastic hip osteoarthritis

PURPOSE

Factors affecting direction of pelvic obliquity (PO) in dysplastic hip osteoarthritis (DHOA) remains unclear. This retrospective cohort study evaluates morphological characteristics, spinal alignment, and hip function in patients with unilateral DHOA.

METHODS

Between 2018 and 2022, 104 patients with unilateral DHA were enrolled. Patients were categorized into flat PO (F-PO group; PO < 2°), affected side PO (A-PO group; PO downward by ≥ 2°), and unaffected side PO (U-PO group; PO upward by ≥ 2°). Demographics, radiographic hip and lower limb parameters, spinal parameters, and functional scores were compared between the groups.

RESULTS

There were 39, 44, and 21 patients in the F-PO, A-PO, and U-PO group, respectively. The subluxation percentage of Crowe classification showed a significant difference among the three groups. The femoral head lateralization distance was significantly greater in the U-PO group than in the F-PO and A-PO groups. Furthermore, the hip adduction angle was significantly lower in the A-PO group than in the F-PO and U-PO groups. The lumbar scoliosis angle was significantly different between the groups. In multivariate analysis, hip adduction angle was extracted as an independent factor associated with the A-PO. Age, subluxation percentage, and hip adduction angle were identified as independent factors associated with the U-PO. Harris hip score was significantly poorer in U-PO group than in F-PO group.

CONCLUSIONS

Hip adduction angle influenced A-PO, while age, subluxation percentage, and hip adduction angle influenced U-PO; lumbar scoliosis angle was associated with PO direction. U-PO patients had poorer functional scores, indicating the impact of hip contracture and subluxation on PO direction in DHOA.

Sagittal-spinopelvic alignment improves in patients with bilateral highly dislocated hip (Crowe type IV) after subtrochanteric shortening total hip arthroplasty: A retrospective radiographic study

In patients with bilateral highly dislocated hips (HDHs), total hip arthroplasty with subtrochanteric shortening osteotomy (S-THA) is a viable option for achieving adequate reconstruction with restoration of the anatomical hip center. This procedure has the potential to improve sagittal spinopelvic alignment (SSPA). However, reports are scarce owing to the rarity of this disease. The objective of this study is to investigate pre- and post-operative SSPA in patients with HDHs who had undergone S-THA. This retrospective radiographic study included 55 patients (54 females and 1 male; average age, 63.1 ± 6.9 years) who underwent S-THA. Lateral spine radiographs in the standing position were obtained pre- and post-operatively. The SSPA included lumbar lordosis (LL), sacral slope (SS), pelvic incidence (PI), and intervertebral disc (ID) angle of L1/2-L5/S. The SSPA pre- and post-S-THA was compared using a paired t test. Pearson correlation coefficient was used to assess the relationships between parameters. The mean pre- and post-operative LL and SS values were 62° and 49° (LL) and 50° and 39° (SS), respectively (P < .001). The ID angle was significantly reduced post-operatively at all levels (P < .001). The correlation coefficients between preoperative LL and SS and postoperative LL and PI were 0.81 and 0.38, respectively (P < .01). The preoperative SSPA of Crowe type IV HDHs revealed excessive pelvic anteversion and lumbar hyperlordosis, with a high correlation between LL and SS, suggesting that these alterations were compensatory changes to maintain body balance. Furthermore, in patients with HDHs and residual spinal flexibility, restoring the original pelvic morphology with S-THA may contribute to improved SSPA.