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Background Structural hip deformities including developmental dysplasia of the hip (DDH) and femoroacetabular impingement (FAI) are thought to predispose patients to degenerative joint changes. However, the natural history of these malformations is not clearly delineated. Questions/purposes (1) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what is the natural history and progression of osteoarthritis in the native hip based on morphological characteristics? (2) Among patients undergoing unilateral THA who have a contralateral hip without any radiographic evidence of hip disease, what are the radiographic parameters that predict differential rates of degenerative change? Methods We identified every patient 55 years of age or younger at our institution who received unilateral primary THA from 1980 to 1989 (n = 722 patients). Preoperative radiographs were reviewed on the contralateral hip and only hips with Tönnis Grade 0 degenerative change that had minimum 10-year radiographic followup were included. A total of 172 patients met all eligibility criteria with the following structural diagnoses: 48 DDH, 74 FAI, and 40 normal morphology, and an additional 6% (10 of the 172 patients) met all eligibility criteria but were lost to followup before the 10-year minimum. Mean age at the time of study inclusion was 47 years (range, 18–55 years), and 56% (91 of 162) of the patients in this study were female. Mean followup was 20 years (range, 10–35 years). Radiographic metrics, in conjunction with the review of two experienced arthroplasty surgeons, determined the structural hip diagnosis as DDH, FAI, or normal morphology. Every available followup AP radiograph was reviewed to determine progression from Tönnis Grade 0 to 3 until the time of last followup or operative intervention with THA. Survivorship was analyzed by Kaplan-Meier methodology, hazard ratios, and multistate modeling. Thirty-five patients eventually underwent THA: 16 (33%) DDH, 13 (18%) FAI, and six (15%) normal morphology. Results Degenerative change was most rapid in patients with DDH followed by FAI and normal morphology. Among patients who recently developed Tönnis 1 degenerative change, the probability of undergoing THA in 10 years based on hip morphology was approximately one in three for DDH and one in five for both FAI and normal morphology hips, whereas the approximate probability at 20 years was two in three for DDH and one in two for both FAI and normal morphology hips. The likelihood of radiographic degeneration was increased in patients with the following findings: femoral head lateralization > 8 mm, femoral head extrusion index > 0.20, acetabular depth-to-width index < 0.30, lateral center-edge angle < 25°, and Tönnis angle > 8°. Conclusions Degenerative change occurred earliest in patients with DDH, whereas the natural history of patients with FAI was quite similar to structurally normal hips. However, patients with cam deformities and concomitant acetabular dysplasia developed osteoarthritis more rapidly. Although the results of this study cannot be directly correlated to highly active patients with FAI, these findings suggest that correction of FAI to a normal morphology may only minimally impact the natural history, especially if intervention takes place beyond Tönnis 0. Analysis of radiographic parameters showed that incremental changes toward dysplastic morphology increase the risk of degenerative change. Level of Evidence Level III, prognostic study.

Background Since its first description in 1984, periacetabular osteotomy (PAO) has become an accepted treatment for hip dysplasia. The 30-year survivorship with this procedure has not been reported. Because these patients are often very young at the time of surgery, long-term followup and identification of factors associated with poor outcome could help to improve patient selection. Questions/purposes Looking at the initial group of patients with hip dysplasia undergoing PAO at the originator’s institution, we asked: (1) What is the cumulative 30-year survival rate free from conversion to THA, radiographic progression of osteoarthritis, and/or a Merle d’Aubigné-Postel score < 15? (2) Did hip function improve and pain decrease? (3) Did radiographic osteoarthritis progress? (4) What are the factors associated with one or more of the three endpoints: THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15? Methods We retrospectively evaluated the first 63 patients (75 hips) who underwent PAO for hip dysplasia between 1984 and 1987. At that time, hip dysplasia was the only indication for PAO and no patients with acetabular retroversion, the second indication for a PAO performed today, were included. During that period, no other surgical treatment for hip dysplasia in patients with closed triradiate cartilage was performed. Advanced osteoarthritis (≥ Grade 2 according to Tönnis) was present preoperatively in 18 hips (24%) and 22 patients (23 hips [31%]) had previous femoral and/or acetabular surgery. Thirty-nine patients (42 hips [56%]) were converted to a THA and one patient (one hip [1%]) had hip fusion at latest followup. Two patients (three hips [4%]) died from a cause unrelated to surgery 6 and 16 years after surgery with an uneventful followup. From the remaining 21 patients (29 hips), the mean followup was 29 years (range, 27–32 years). Of those, five patients (six hips [8%]) did not return for the most recent followup and only a questionnaire was available. The cumulative survivorship of the hip according to Kaplan-Meier was calculated if any of the three endpoints, including conversion to THA, progression of osteoarthritis by at least one grade according to Tönnis, and/or a Merle d’Aubigné-Postel score < 15, occurred. Hip pain and function were assessed with Merle d’Aubigné-Postel score, Harris hip score, limp, and anterior and posterior impingement tests. Progression of radiographic osteoarthritis was assessed with Tönnis grades. A Cox regression model was used to calculate factors associated with the previously defined endpoints. Results The cumulative survivorship free from conversion to THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15 was 29% (95% confidence interval, 17%-42%) at 30 years. No improvement was found for either the Merle d’Aubigné-Postel (15 ± 2 versus 16 ± 2, p = 0.144) or Harris hip score (83 ± 11 versus 85 ± 17, p = 0.602). The percentage of a positive anterior impingement test (39% versus 14%, p = 0.005) decreased at 30-year followup, whereas the percentage of a positive posterior impingement test (14% versus 3%, p = 0.592) did not decrease. The percentage of positive limp decreased from preoperatively 66% to 18% at 30-year followup (p < 0.001). Mean osteoarthritis grade (Tönnis) increased from preoperatively 0.8 ± 1 (0–3) to 2.1 ± 1 (0–3) at 30-year followup (p < 0.001). Ten factors associated with poor outcome defined as THA, radiographic progression of osteoarthritis, and/or Merle d’Aubigné-Postel score < 15 were found: preoperative age > 40 years (hazard ratio [HR] 4.3 [3.7–4.9]), a preoperative Merle d’Aubigné-Postel score < 15 (HR 4.1 [3.5–4.6]), a preoperative Harris hip score < 70 (HR 5.8 [5.2–6.4]), preoperative limp (HR 1.7 [1.4–1.9]), presence of a preoperative positive anterior impingement test (HR 3.6 [3.1–4.2]), presence of a preoperative positive posterior impingement test (HR 2.5 [1.7–3.2]), a preoperative internal rotation of < 20° (HR 4.3 [3.7–4.9]), a preoperative Tönnis Grade > 1 (HR 5.7 [5.0–6.4]), a postoperative anterior coverage > 27% (HR 3.2 [2.5–3.9]), and a postoperative acetabular retroversion (HR 4.8 [3.4–6.3]). Conclusions Thirty years postoperatively, 29% of hips undergoing PAO for hip dysplasia can be preserved, but more than 70% will develop progressive osteoarthritis, pain, and/or undergo THA. Periacetabular osteotomy is an effective technique to treat symptomatic hip dysplasia in selected and young patients with closed triradiate cartilage. Hips with advanced joint degeneration (osteoarthritis Tönnis Grade ≥ 2) should not be treated with PAO. Postoperative anterior acetabular overcoverage or postoperative acetabular retroversion were associated with decreased joint survival. Level of Evidence Level III, therapeutic study.

Background Hip dysplasia is a common cause of secondary osteoarthritis (OA). Periacetabular osteotomy or rotational acetabular osteotomy has been used as joint-preserving procedures. However, only a few reports of long-term results with these operations have been reported. Questions/purposes (1) Would satisfactory clinical and radiographic outcomes be maintained at a mean duration of 20 years after rotational acetabular osteotomy for pre- and early-stage OA; and (2) could we identify risk factors for radiographic progression of OA? Methods Between 1987 and 2001, we treated 159 patients (173 hips) with rotational acetabular osteotomies for the diagnosis of pre-OA or early-stage OA according to the technique of Ninomiya and Tagawa. During that period, our general indications for this approach were age younger than 60 years, center-edge angle less than 20°, and improved femoral head coverage and joint congruency on preoperative AP plain radiographs of the hip in abduction; we did not use this approach when joint congruency was not improved or no widening of the joint space was noted on preoperative AP plain radiographs of the hip in abduction. Of those patients, 21 patients with pre-OA (followup rate: 84% [27 hips]) and 110 patients in the early-stage group (followup rate: 82% [118 hips]) were available at a minimum of 15 years for a total patient group of 131 (followup rate: 82% [145 hips]). The mean age at the time of surgery was 22 years in the pre-OA group and 38 years in the early-stage group. The mean followup was 21 years in the pre-OA group and 20 years in the early-stage group. Clinical evaluation was performed with the Merle d’Aubigne and Postel rating scale, and radiographic analyses included measurements of the center-edge angle, acetabular roof angle, and head lateralization index on preoperative and postoperative AP radiographs of the pelvis. Postoperative joint congruency was also evaluated. The cumulative probabilities of radiographic signs of OA progression were estimated with use of the Kaplan-Meier product-limited method and parametric survivorship analysis using the Cox proportional-hazards model was used to determine risk factors for radiographic OA progression. Results The mean clinical score improved very slightly, from 15 (SD, 0.8) to 18 (SD, 1.1) (95% confidence interval [CI], −2.9 to −2.0; p < 0.001) in the pre-OA group and from 15 (SD, 1.0) to 16 (SD, 2.1) (95% CI, −2.0 to −1.2; p < 0.001) in the early-stage group at followup. Fourteen patients (15 hips) including one pre-OA patient (one hip) and 13 early-stage patients (14 hips) experienced worsening of their Merle d’Aubigne and Postel score, from a mean of 15 (SD, 0.9) to 12 (SD, 1.6) (95% CI, 1.8–3.3; p < 0.001). Eight patients (nine hips) with early-stage OA preoperatively underwent total hip arthroplasty at a mean duration after rotational acetabular osteotomy of 20 (SD, 2.5) years. Radiographic indices were improved after surgery in both groups. Radiographic progression of OA occurred in 24 patients (25 hips). Kaplan-Meier survivorship analysis, with radiographic signs of progression of OA as the endpoint, predicted survival of 96% (95% CI, 89%–100%) at 10 years and 20 years in the pre-OA group. For the early-stage group, we found survivorship of 89% (95% CI, 83%–95%) at 10 years and 78% (95% CI, 69%–87%) at 20 years. We identified two factors associated with poor outcome: fair (rather than excellent and good) postoperative joint congruency (hazard ratio, 12.1; 95% CI, 3.8–39; p < 0.001) and age older than 46 years at the time of surgery (hazard ratio, 4.6; 95% CI, 1.9–11; p < 0.01). Conclusions Rotational acetabular osteotomy is an effective surgical procedure for symptomatic dysplastic hips in pre- and early-stage OA, and it prevented radiographic OA progression and maintained hip function at a mean 20 years after surgery. Level of Evidence Level IV, therapeutic study.

Background There are many factors that may affect the learning curve for total hip arthroplasty (THA) and surgical approach is one of these. There has been renewed interest in the direct anterior approach for THA with variable outcomes reported, but few studies have documented a surgeon’s individual learning curve when using this approach. Questions/purposes (1) What was the revision rate for all surgeons adopting the anterior approach for placement of a particular implant? (2) What was the revision rate for surgeons who performed > 100 cases in this fashion? (3) Is there a minimum number of cases required to complete a learning curve for this procedure? Methods The Australian Orthopaedic Association National Joint Replacement Registry prospectively collects data on all primary and revision joint arthroplasty surgery. We analyzed all conventional THAs performed up to December 31, 2013, with a primary diagnosis of osteoarthritis using a specific implant combination and secondarily those associated with surgeons performing more than 100 procedures. Ninety-five percent of these procedures were performed through the direct anterior approach. Procedures using this combination were ordered from earliest (first procedure date) to latest (last procedure date) for each individual surgeon. Using the order number for each surgeon, five operation groups were defined: one to 15 operations, 16 to 30 operations, 31 to 50 operations, 51 to 100 operations, and > 100 operations. The primary outcome measure was time to first revision using Kaplan-Meier estimates of survivorship. Results Sixty-eight surgeons performed 5499 THAs using the specified implant combination. The cumulative percent revision at 4 years for all 68 surgeons was 3% (95% confidence interval [CI], 2.5–3.8). For surgeons who had performed over 100 operations, the cumulative revision rate was 3% (95% CI, 2.0–3.5). It was not until surgeons had performed over 50 operations that there was no difference in the cumulative percent revision compared with over 100 operations. The cumulative percent revision for surgeons performing 51 to 100 operations at 4 years was 3% (95% CI, 1.5–5.4) and over 100 operations 2% (95% CI, 1.2–2.7; hazard ratio, 1.40 [95% CI, 0.7–2.7]; p = 0.33). Conclusions There is a learning curve for the anterior approach for THA even when using a prosthesis combination specifically marketed for that approach. We found that 50 or more procedures need to be performed by a surgeon before the rate of revision is no different from performing 100 or more procedures. Surgeons should be aware of this initial higher rate of revision when deciding which approach delivers the best outcome for their patients.

Background Numerous factors influence total hip arthroplasty (THA) stability including surgical approach and soft tissue tension, patient compliance, and component position. One long-held tenet regarding component position is that cup inclination and anteversion of 40° ± 10° and 15° ± 10°, respectively, represent a “safe zone” as defined by Lewinnek that minimizes dislocation after primary THA; however, it is clear that components positioned in this zone can and do dislocate. Questions/purposes We sought to determine if these classic radiographic targets for cup inclination and anteversion accurately predicted a safe zone limiting dislocation in a contemporary THA practice. Methods From a cohort of 9784 primary THAs performed between 2003 and 2012 at one institution, we retrospectively identified 206 THAs (2%) that subsequently dislocated. Radiographic parameters including inclination, anteversion, center of rotation, and limb length discrepancy were analyzed. Mean followup was 27 months (range, 0–133 months). Results The majority (58% [120 of 206]) of dislocated THAs had a socket within the Lewinnek safe zone. Mean cup inclination was 44° ± 8° with 84% within the safe zone for inclination. Mean anteversion was 15° ± 9° with 69% within the safe zone for anteversion. Sixty-five percent of dislocated THAs that were performed through a posterior approach had an acetabular component within the combined acetabular safe zones, whereas this was true for only 33% performed through an anterolateral approach. An acetabular component performed through a posterior approach was three times as likely to be within the combined acetabular safe zones (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.1–1.6) than after an anterolateral approach (OR, 0.4; 95% CI, 0.2–0.7; p < 0.0001). In contrast, acetabular components performed through a posterior approach (OR, 1.6; 95% CI, 1.2–1.9) had an increased risk of dislocation compared with those performed through an anterolateral approach (OR, 0.8; 95% CI, 0.7–0.9; p < 0.0001). Conclusions The historical target values for cup inclination and anteversion may be useful but should not be considered a safe zone given that the majority of these contemporary THAs that dislocated were within those target values. Stability is likely multifactorial; the ideal cup position for some patients may lie outside the Lewinnek safe zone and more advanced analysis is required to identify the right target in that subgroup. Level of Evidence Level III, therapeutic study.

This two volume set contains comprehensive coverage of management of disorders of the adult hip. It includes all arthroscopic and open procedures as well as extensive coverage of equipment and prostheses.

Background Despite the overall effectiveness of total hip arthroplasty (THA), a subset of patients remain dissatisfied with their results because of persistent pain or functional limitations. It is therefore important to develop predictive tools capable of identifying patients at risk for poor outcomes before surgery. Questions/purposes The purpose of this study was to use preoperative patient-reported outcome measure (PROM) scores to predict which patients undergoing THA are most likely to experience a clinically meaningful change in functional outcome 1 year after surgery. Methods A retrospective cohort study design was used to evaluate preoperative and 1-year postoperative SF-12 version 2 (SF12v2) and Hip Disability and Osteoarthritis Outcome Score (HOOS) scores from 537 selected patients who underwent primary unilateral THA. Minimum clinically important differences (MCIDs) were calculated using a distribution-based method. A receiver operating characteristic analysis was used to calculate threshold values, defined as the levels at which substantial changes occurred, and their predictive ability. MCID values for HOOS and SF12v2 physical component summary (PCS) scores were calculated to be 9.1 and 4.6, respectively. We analyzed the effect of SF12v2 mental component summary (MCS) scores, which measure mental and emotional health, on SF12v2 PCS and HOOS threshold values. Results Threshold values for preoperative HOOS and PCS scores were a maximum of 51.0 (area under the curve [AUC], 0.74; p < 0.001) and 32.5 (AUC, 0.62; p < 0.001), respectively. As preoperative mental and emotional health improved, which was reflected by a higher MCS score, HOOS and PCS threshold values also increased. When preoperative mental and emotional health were taken into account, both HOOS and PCS threshold values’ predictive ability improved (AUCs increased to 0.77 and 0.69, respectively). Conclusions We identified PROM threshold values that predict clinically meaningful improvements in functional outcome after THA. Patients with a higher level of preoperative function, as suggested by HOOS or PCS scores above the defined threshold values, are less likely to obtain meaningful improvement after THA. Lower preoperative mental and emotional health decreases the likelihood of achieving a clinically meaningful improvement in function after THA. The results of this study may be used to facilitate discussion between physicians and patients regarding the expected benefit after THA and to support the development of patient-based informed decision-making tools. For example, despite significant disease, patients with high preoperative function, as measured by PROM scores, may choose to delay surgery given the low likelihood of experiencing a meaningful improvement postoperatively. Similarly, patients with notably low MCS scores might best be counseled to address mental health issues before embarking on surgery. Level of Evidence Level III, prognostic study.

IntroductionThe significance of the relationship between the spine and hip joints has been frequently discussed. However, the relationship between acetabular coverage and spinal sagittal alignment has not been fully elucidated as previous studies did not adequately control for factors that might affect the spinopelvic alignment. The aim of this study was to elucidate the impact of acetabular coverage on spinal sagittal alignment by comparing patient groups matched on sex, age, and the presence of hip and anterior impingement pain.Materials and methodsWe prospectively enrolled 30 women undergoing periacetabular osteotomy (PAO) for developmental dysplasia of the hip (DDH) and 30 women undergoing hip arthroscopic surgery (HAS) for labral tears. The lateral centre edge angle was measured on hip radiographs. In addition, the sagittal vertical axis, pelvic tilt, pelvic incidence, sacral slope (SS), and lumbar lordosis (LL) were measured on preoperative plain radiographs of the whole spine to assess the sagittal spinal alignment. Clinical and radiologic data were compared between the two groups (PAO vs. HAS).ResultsThe patient groups did not differ in age and body mass index. The mean SS was significantly greater in the PAO group (41.6° ± 1.6°) than in the HAS group (35.3° ± 1.5°; P = 0.0039). Additionally, the mean LL was significantly greater in the PAO group (54.5° ± 2.0°) than in the HAS group (45.1° ± 1.9°; P = 0.0015).ConclusionsThe SS and LL were greater in patients with DDH than in patients with hip pain, but without DDH. Patients with DDH might show lumbar hyperlordosis to rotate the pelvis anteriorly, increasing the anterosuperior acetabular coverage.

IntroductionTotal hip arthroplasty (THA) is a good option as a salvage procedure after failed treatment of proximal femur fracture. The anatomy of the proximal femur, however, makes this surgery complicated and challenging. The purpose of this study was to evaluate the radiographic and clinical outcomes of THA after failed treatment of proximal femur fractures.Materials and methodsWe retrospectively analysed 50 consecutive THAs (42 women, 8 men; mean age 77 years) after failed treatment of a proximal femur fracture. Mean postoperative follow-up was 58.1 months. Preoperative diagnoses were femoral neck fracture in 18 hips and trochanteric fracture in 32 hips, including three that were infected. Failure resulted from cutout in 22 cases, osteonecrosis in 12, non-union with failed fixation in nine, postoperative osteoarthritis in four, and infection in three. Factors compared included radiographic assessment, complication rate, visual analogue scale (VAS), and Harris Hip Scores (HHS). Radiographic variables included femoral neck anteversion and cup and stem alignment.ResultsAbsolute values of the differences in femoral neck anteversion between the affected and healthy sides were 6.0° in the femoral neck fracture group and 19.2° in the trochanteric fracture group (p = 0.01). There were no significant differences in cup anteversion (p = 0.20) or stem anteversion (p = 0.08). The complication rate was significantly higher in the trochanteric fracture group than in the femoral neck fracture group (25 vs 0%, p < 0.0001). Postoperative complications in the trochanteric fracture group included three periprosthetic fractures (9.4%), two dislocations (6.3%), two surgical-site infections (6.3%), and one stem penetration (3.1%). Although no significant differences between groups were seen in the VAS or HHS at final follow-up (p = 0.32, 0.09, respectively), these measures were significantly improved at final follow-up in both groups (p < 0.0001 for both).ConclusionsPerforming THA after failed treatment of trochanteric fractures requires consideration of complication risk and incorrect femoral neck anteversion.

Total joint replacements for end-stage osteoarthritis of the hip and knee are cost-effective and demonstrate significant clinical improvement. However, robust population based lifetime-risk data for implant revision are not available to aid patient decision making, which is a particular problem in young patient groups deciding on best-timing for surgery. We did implant survival analysis on all patients within the Clinical Practice Research Datalink who had undergone total hip replacement or total knee replacement. These data were adjusted for all-cause mortality with data from the Office for National Statistics and used to generate lifetime risks of revision surgery based on increasing age at the time of primary surgery. We identified 63 158 patients who had undergone total hip replacement and 54 276 who had total knee replacement between Jan 1, 1991, and Aug 10, 2011, and followed up these patients to a maximum of 20 years. For total hip replacement, 10-year implant survival rate was 95·6% (95% CI 95·3–95·9) and 20-year rate was 85·0% (83·2–86·6). For total knee replacement, 10-year implant survival rate was 96·1% (95·8–96·4), and 20-year implant survival rate was 89·7% (87·5–91·5). The lifetime risk of requiring revision surgery in patients who had total hip replacement or total knee replacement over the age of 70 years was about 5% with no difference between sexes. For those who had surgery younger than 70 years, however, the lifetime risk of revision increased for younger patients, up to 35% (95% CI 30·9–39·1) for men in their early 50s, with large differences seen between male and female patients (15% lower for women in same age group). The median time to revision for patients who had surgery younger than age 60 was 4·4 years. Our study used novel methodology to investigate and offer new insight into the importance of young age and risk of revision after total hip or knee replacement. Our evidence challenges the increasing trend for more total hip replacements and total knee replacements to be done in the younger patient group, and these data should be offered to patients as part of the shared decision making process. Oxford Musculoskeletal Biomedical Research Unit, National Institute for Health Research.