Functional Improvement and Patient Satisfaction Following Conversion of Fused Hip to Total Hip Arthroplasty.

BACKGROUND: This study aimed to determine the clinical outcomes, predictors of suboptimal functional improvement, and factors influencing patient satisfaction following conversion of a fused hip to total hip arthroplasty (THA). METHODS: A retrospective analysis of clinical and radiographic data was performed on 83 patients (83 hips) who underwent fused hip conversion to THA. Implant survival and predictors of poor functional outcome (Harris hip score < 70) were analyzed. In addition, factors associated with patient dissatisfaction (visual analog scale < 25th percentile) were analyzed in 63 patients (63 hips) who completed a patient-reported outcome measures questionnaire. RESULTS: The median Harris hip score improved from 55 (range, 18 to 77) to 78 (range, 36 to 100) at a mean follow-up of 10.2 ± 4.8 years (P < .001). Implant survival was 97.4% at 10 years and 91.3% at 20 years, with any revision as the endpoint. Multivariate analysis identified preoperative reliance on mobility aids as an independent predictor of poor functional outcome (P = .021). There were 48 of 63 patients (76%) satisfied (satisfaction visual analog scale ≥80) with the operated hip. Demographics and preoperative/postoperative clinical data did not differ between satisfied and unsatisfied patients. Among the patient-reported outcome measures, the Forgotten Joint Score-12 emerged as an independent discriminator of patient satisfaction. CONCLUSIONS: Conversion of a fused hip to THA provides functional improvement, favorable implant survival, and high patient satisfaction. However, patients dependent on mobility aids may experience suboptimal functional recovery, underscoring the need for careful preoperative counseling and patient selection.

Neurovascular Structural Deviations in Patients Who Have Fused Hips: Implications for Total Hip Arthroplasty.

BACKGROUND: The purpose of this study was to compare the fused and normal sides of patients who have fused hips to determine the differences in neurovascular structures and factors that increase the risk of neurovascular injury. METHODS: We evaluated 38 patients who underwent total hip arthroplasty, with a fused hip between 2003 and 2021. Excluding patients who had bilateral lesions, differences in the location of neurovascular structures were measured by comparing the fused side with the normal side. The position of neurovascular structures was measured by the distance from the acetabular rim and the shortest distance to the particular bony structure. In addition, the patient's sex, weight, body mass index cause of fused hips, estimated age of fusion onset, and preoperative range of motion were investigated to examine the correlations with neurovascular deviation and these factors. RESULTS: The neurovascular distances for all the measured neurovascular structures were significantly reduced on the fused side compared with the normal side. Sex-based analysis revealed that women had significantly shorter distances to the femoral neurovascular bundle than men. Although height and body weight were associated with differences in neurovascular distances, body mass index was not associated with significant differences, except for the femoral nerve distance from the nearest bone. When classified by the estimated age of fusion onset, significant differences in neurovascular distances were found between the adolescent- and adult-onset groups. CONCLUSIONS: In patients who have fused hips, neurovascular structures are located closer to the bone than on the normal side. Moreover, patients in whom the fusion occurred before the completion of growth may exhibit a shorter neurovascular distance, thereby increasing the potential risk of direct injury during total hip arthroplasty .

Conversion of Fused Hip to Total Hip Arthroplasty: Long-Term Clinical and Radiological Outcomes.

BACKGROUND: Despite promising results at the mid-term followup, several aspects of conversion of the fused hip to total hip arthroplasty (THA) remain controversial. The aim of this study was to evaluate clinical and radiological outcomes with a minimum 5-year followup in patients who underwent conversion of the fused hip to THA. METHODS: Fifty-seven patients (59 hips) were evaluated. The Harris Hip Score (HHS), range of motion (ROM), and the Visual Analogue Scale (VAS) were used to assess hip function and low back pain. Subjective satisfaction with surgery and the presence of the Trendelenburg sign was also evaluated. Radiological assessment was performed pre- and postoperatively to evaluate loosening and heterotopic ossification (HO). RESULTS: After a mean followup of 13.0 ± 6.2 years, HHS and VAS significantly improved from 46.0 ± 16.7 to 80.8 ± 18.8 and from 4.4 ± 1.5 to 2.1 ± 1.4 (both P < .001), respectively. Twenty-three patients (40.4%) had a positive Trendelenburg sign, and HOs were found in 29 cases (49.1%). An overall 29.8% complication rate was noted. Smoking habits and rheumatoid arthritis were predictive of Trendelenburg sign (P = .046 and P = .038, respectively). Implant survival rate as the end point was 98.7 ± 1.3% at 5 years, 92.4 ± 3.3% at 10 years, 82.1 ± 5.7% at 15 years, and 73.4 ± 8.0% at 20 and 25 years. A worse cumulative implant survival rate was noted in patients who underwent previous hip surgery, defined as any hip operation before fusion (P = .005). CONCLUSION: Conversion of the fused hip to hip arthroplasty provides high levels of hip functionality and satisfaction with surgery at long-term followup. An implant survival rate higher than 70% can be expected 25 years postoperatively.

Risk Factors of Heterotopic Ossification Following Total Hip Arthroplasty in Patients With Ankylosing Spondylitis.

This study was to identify the risk factors of heterotopic ossification (HO) after total hip arthroplasty (THA) in ankylosing spondylitis. We analyzed 47 hips (24 patients) with ankylosing spondylitis that underwent primary THA. The incidence of HO was 14.9%. The risk factors were divided into modifiable and nonmodifiable factors. Female gender (P=0.008), preoperative ankylosed hip (P<0.001), occurrence of HO in previous surgery (P=0.036) were nonmodifiable risk factors which increased the prevalence of HO. Of the various modifiable risk factors, elevated preoperative ESR (P=0.007), elevated preoperative CRP (P=0.004) and prolonged duration of surgery (P=0.014) were associated with increased occurrence of HO. Perioperative medical intervention to reduce inflammation (ESR and CRP) may help to decrease HO.

[Effectiveness analysis of MAKO robotic-arm assisted total hip arthroplasty via direct anterior approach for bony fused hips].

Objective: To investigate the effectiveness of MAKO robotic-arm assisted total hip arthroplasty (THA) via direct anterior approach (DAA) for bony fused hips in ankylosing spondylitis (AS). Methods: Between June 2021 and January 2022, MAKO robotic-arm assisted THA via DAA was applied to treat 10 cases (12 hips) of AS with bony fused hips. There were 7 males and 3 females; the age ranged from 30 to 71 years, with an average age of 42.4 years. The duration of AS was 12-35 years, with an average of 21.4 years. The preoperative hip was ankylosed in flexion in 3 cases, with a flexion angle of 20°, 30°, 35°, respectively; 9 cases were ankylosed in extension. The operation time and complications were recorded; the visual analogue scale (VAS) score, Harris score, and Oxford hip scale (OHS) score before and after operation, and postoperative range of motion (flexion, extension, internal rotation, external rotation, adduction, and abduction) were used to evaluate the recovery of joint function; according to the postoperative anteroposterior X-ray film and CT scan of both hip joints, the abduction angle, anteversion angle, the difference between bilateral combined off-set and the lower limb length discrepancy were measured. Results: The operation time ranged from 80 to 190 minutes (mean, 134.6 minutes). All 10 patients were followed up 5-11 months (mean, 7.4 months). There was no serious adverse events such as incision infection, deep vein thrombosis of lower extremities, hip redislocation, aseptic loosening of the prosthesis, or death. At 5 months after operation, the acetabular prosthesis angle of abduction was 37°-45° (mean, 40.3°), anteversion angle was 9°-20° (mean, 15.8°). The difference between bilateral combined off-set was 0-10 mm (mean, 4.3 mm); the lower limb length discrepancy was 0-12 mm (mean, 3.5 mm). At last follow-up, the average range of motion of the hip joint was 89.2° in flexion (range, 80°-100°), 1.7° in extension (range, -5°-10°), 7.1° in internal rotation (range, 0°-15°), 20.4° in external rotation (range, 10°-30°), 7.9° in adduction (range, 0°-20°), and 16.5° in abduction (range, 10°-25°). At last follow-up, the VAS score, Harris score, and OHS score significantly improved when compared with those before operation ( P<0.05). Conclusion: The MAKO robotic-arm assisted THA via DAA can achieve satisfactory results in the treatment of AS with bony fused hip, which has the advantages of accurate prosthesis installation, soft tissue release, and less trauma during operation.

Does the Femoral Head Size Influence Outcomes After Uncemented Total Hip Arthroplasty for Fused Hips? A Prospective Study in Ankylosing Spondylitis.

BACKGROUND: Uncemented total hip arthroplasty (THA) with large size femoral heads have shown greater advantage with good stability, range of motion and decreased dislocation rate in ankylosing spondylitis (AS). Meticulous planning is needed to address the unique surgical challenges in such patients with fused hip and spinal deformity. MATERIALS AND METHODS: Thirty fivefused hip joints in twenty-five AS patients who underwent uncemented THA (April 2014 to December 2016) were included in our prospective study and were followed up for a minimum period of 36 months. Pain relief, functional improvement and patient satisfaction were statistically assessed using "Visual Analogue Score" (VAS), "Harris Hip Score" (HHS) and "AJRI 10-Point Satisfaction Score" (A10PSS), respectively. RESULTS: The overall mean preoperative VAS improved from 6.9 ± 1.5 to 1.5 ± 1, HHS improved from 50.0 ± 12 to 88.4 ± 7.8 and A10PSS improved from 2.2 ± 1.2 to 7.6 ± 0.8. Our study results were significant with zero dislocation and good functional score in comparison to the other available studies in literature. First subdivision study in AS patients with bilateral THA performed better than unilateral THA. Second subdivision study showed no significant statistical difference in terms of VAS, HHS, A10PSS and dislocation rate in relation to femoral head size between 32 mm, 36 mm and 40 mm. CONCLUSION: Uncemented THA with large size femoral head equal or greater than 32 mm provides better stability and good functional outcome with less dislocation rate in comparison to older studies of literature with femoral head size less than 32 mm. LEVEL OF EVIDENCE: A Level II study. (Data collected from the ongoing prospective study) (https://www.spine.org/Documents/LevelsofEvidenceFinal.pdf).

Clinical Evaluation of Fused/Ankylosed Hip with Severe Flexion Deformity after Conversion to Total Hip Arthroplasty.

INTRODUCTION: Fused or Ankylosed hip is late complication of chronic inflammatory disorder with progressive changes in and around articular as well as periarticular structures with alteration in bio-force line of body which later lead to severe flexion deformity of joint. This not only results decreased movements of hip, it's also increase pain around the hip, back and contralateral hip. METHODS: Retrospectively, all patients aged 18 years or older undergoing THA between June 2006 to June 2012 were reviewed with selection criteria. The five ankylosed hips (three left and two right) with severe flexion deformities which ankylosed spontaneously were successfully converted to THA at time period of 2006 to June 2012. Range of motion, Harris Hip Score and flexion deformity angle at preoperative, postoperative and follow-up periods were used as evaluation. RESULTS: Mean follow up is 42 months. Mean HHS increased from 21.6±4.97 to 81.8±4.02 points with one excellent, two good and two fair cases. The FDA is corrected to mean 8°±10.95 postoperatively and 4°±5.47 at final follow up from 81.6°±4.39 with two hips of 10° residual deformity. Hip ROM is improved as flexion 70° to 100°, adduction 10° to 20°, abduction 10° to 30°, internal rotation 5° to 10° and external rotation 2° to 50° from 0° activity. As complications, one hip had loose prosthesis, two had early postoperative dislocations, one had Deep Vein Thrombosis and one had femoral nerve palsy with quadriceps weakness. CONCLUSIONS: THA is an effective treatment for ankylosed hip with severe flexion deformity although complications are noted more than routine hip arthroplasties.

Ceramic on ceramic hip arthroplasty in fused hips.

BACKGROUND: Most literature in the field of total hip arthroplasty (THA) for fused hips, until date has reported the results of using metal on polyethylene and ceramic on polyethylene bearings. Results of THA using ceramic on ceramic (CoC) bearings in fused hips have not been published in literature. This study reports the results of cementless THA using CoC articulation perfomed in fused hips. MATERIALS AND METHODS: Twenty-three patients (25 hips) with fused hips underwent conversion to THA using CoC bearings and were followed up for a mean 5.4 years. The conventional posterolateral approach was used in 15 hips, a modified two incision technique in 7 hips and a direct lateral approach with greater trochanteric osteotomy in 3 hips. Postoperatively, range of motion exercises were encouraged after 2-3 days of bed rest and subsequent gradual weight bearing using crutches was begun. RESULTS: Mean Harris hip score improved from 42.4 to 84.2 and mean leg lengthening of 36.6 mm was achieved. In the average 5.4 years (range 2.8-9.1 years) followup there were no cases with osteolysis around acetabular cup and femoral stem. In this study, there was no case of ceramic fracture. There was one case of squeaking. CONCLUSION: This study suggests that cementless THA performed for fused hips with CoC bearings can provide good early clinical results.