The aim of this study was to investigate the incidence of dysplasia in the ‘normal’ contralateral hip in patients with unilateral developmental dislocation of the hip (DDH) and to evaluate the long-term prognosis of such hips. A total of 48 patients (40 girls and eight boys) were treated for late-detected unilateral DDH between 1958 and 1962. After preliminary skin traction, closed reduction was achieved at a mean age of 17.8 months (4 to 65) in all except one patient who needed open reduction. In 25 patients early derotation femoral osteotomy of the contralateral hip had been undertaken within three years of reduction, and later surgery in ten patients. Radiographs taken during childhood and adulthood were reviewed. The mean age of the patients was 50.9 years (43 to 55) at the time of the latest radiological review. In all, eight patients (17%) developed dysplasia of the contralateral hip, defined as a centre-edge (CE) angle < 20° during childhood or at skeletal maturity. Six of these patients underwent surgery to improve cover of the femoral head; the dysplasia improved in two after varus femoral osteotomy and in two after an acetabular shelf operation. During long-term follow-up the dysplasia deteriorated to subluxation in two patients (CE angles 4° and 5°, respectively) who both developed osteoarthritis (OA), and one of these underwent total hip replacement at the age of 49 years. In conclusion, the long-term prognosis for the contralateral hip was relatively good, as OA occurred in only two hips (4%) at a mean follow-up of 50 years. Regular review of the ‘normal’ side is indicated, and corrective surgery should be undertaken in those who develop subluxation. Cite this article: Bone Joint J 2014; 96-B:1161–6

In the majority of patients with slipped upper femoral epiphysis only one hip is involved at primary diagnosis. However, the contralateral hip often becomes involved over time. There are no reliable factors predicting a contralateral slip. Whether or not the contralateral hip should undergo prophylactic fixation is a matter of controversy. We present a number of essential points that have to be considered both when choosing to fix the contralateral hip prophylactically as well as when refraining from surgery and instead following the patients with repeat radiographs

Aims

The purpose of this study was to examine whether leg-length discrepancy (LLD) following unilateral total hip arthroplasty (THA) affects the incidence of contralateral head collapse and subsequent THA in patients with bilateral osteonecrosis, and to determine factors associated with subsequent collapse.

Aims. Hip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane. Methods. Postoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation. Results. Overall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement. Conclusion. This study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation. Cite this article: Bone Joint Res 2022;11(3):180–188

Aims. This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH). Methods. The study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured. Results. The mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups. Conclusion. We demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH. Cite this article: Bone Joint Res 2021;10(10):629–638

Aims. Spinopelvic mobility plays an important role in functional acetabular component position following total hip arthroplasty (THA). The primary aim of this study was to determine if spinopelvic hypermobility persists or resolves following THA. Our second aim was to identify patient demographic or radiological factors associated with hypermobility and resolution of hypermobility after THA. Methods. This study investigated patients with preoperative posterior hypermobility, defined as a change in sacral slope (SS) from standing to sitting (ΔSS. stand-sit. ) ≥ 30°. Radiological spinopelvic parameters, including SS, pelvic incidence (PI), lumbar lordosis (LL), PI-LL mismatch, anterior pelvic plane tilt (APPt), and spinopelvic tilt (SPT), were measured on preoperative imaging, and at six weeks and a minimum of one year postoperatively. The severity of bilateral hip osteoarthritis (OA) was graded using Kellgren-Lawrence criteria. Results. A total of 136 patients were identified as having preoperative spinopelvic hypermobility. At one year after THA, 95% (129/136) of patients were no longer categorized as hypermobile on standing and sitting radiographs (ΔSS. stand-sit. < 30°). Mean ΔSS. stand-sit. decreased from 36.4° (SD 5.1°) at baseline to 21.4° (SD 6.6°) at one year (p < 0.001). Mean SS. seated. increased from baseline (11.4° (SD 8.8°)) to one year after THA by 11.5° (SD 7.4°) (p < 0.001), which correlates to an 8.5° (SD 5.5°) mean decrease in seated functional cup anteversion. Contralateral hip OA was the only radiological predictor of hypermobility persisting at one year after surgery. The overall reoperation rate was 1.5%. Conclusion. Spinopelvic hypermobility was found to resolve in the majority (95%) of patients one year after THA. The increase in SS. seated. was clinically significant, suggesting that current target recommendations for the hypermobile patient (decreased anteversion and inclination) should be revisited. Cite this article: Bone Joint J 2021;103-B(12):1766–1773

Aims. Cross-table lateral (CTL) radiographs are commonly used to measure acetabular component anteversion after total hip arthroplasty (THA). The CTL measurements may differ by > 10° from CT scan measurements but the reasons for this discrepancy are poorly understood. Anteversion measurements from CTL radiographs and CT scans are compared to identify spinopelvic parameters predictive of inaccuracy. Methods. THA patients (n = 47; 27 males, 20 females; mean age 62.9 years (SD 6.95)) with preoperative spinopelvic mobility, radiological analysis, and postoperative CT scans were retrospectively reviewed. Acetabular component anteversion was measured on postoperative CTL radiographs and CT scans using 3D reconstructions of the pelvis. Two cohorts were identified based on a CTL-CT error of ≥ 10° (n = 11) or < 10° (n = 36). Spinopelvic mobility parameters were compared using independent-samples t-tests. Correlation between error and mobility parameters were assessed with Pearson’s coefficient. Results. Patients with CTL error > 10° (10° to 14°) had stiffer lumbar spines with less mean lumbar flexion (38.9°(SD 11.6°) vs 47.4° (SD 13.1°); p = 0.030), different sagittal balance measured by pelvic incidence-lumbar lordosis mismatch (5.9° (SD 18.8°) vs -1.7° (SD 9.8°); p = 0.042), more pelvic extension when seated (pelvic tilt -9.7° (SD 14.1°) vs -2.2° (SD 13.2°); p = 0.050), and greater change in pelvic tilt between supine and seated positions (12.6° (SD 12.1°) vs 4.7° (SD 12.5°); p = 0.036). The CTL measurement error showed a positive correlation with increased CTL anteversion (r = 0.5; p = 0.001), standing lordosis (r = 0.23; p = 0.050), seated lordosis (r = 0.4; p = 0.009), and pelvic tilt change between supine and step-up positions (r = 0.34; p = 0.010). Conclusion. Differences in spinopelvic mobility may explain the variability of acetabular anteversion measurements made on CTL radiographs. Patients with stiff spines and increased compensatory pelvic movement have less accurate measurements on CTL radiographs. Flexion of the contralateral hip is required to obtain clear CTL radiographs. In patients with lumbar stiffness, this movement may extend the pelvis and increase anteversion of the acetabulum on CTL views. Reliable analysis of acetabular component anteversion in this patient population may require advanced imaging with a CT scan. Cite this article: Bone Joint J 2021;103-B(7 Supple B):59–65

Aims. Surgical treatment of young femoral neck fractures often requires an open approach to achieve an anatomical reduction. The application of a calcar plate has recently been described to aid in femoral neck fracture reduction and to augment fixation. However, application of a plate may potentially compromise the regional vascularity of the femoral head and neck. The purpose of this study was to investigate the effect of calcar femoral neck plating on the vascularity of the femoral head and neck. Methods. A Hueter approach and capsulotomy were performed bilaterally in six cadaveric hips. In the experimental group, a one-third tubular plate was secured to the inferomedial femoral neck at 6:00 on the clockface. The contralateral hip served as a control with surgical approach and capsulotomy without fixation. Pre- and post-contrast MRI was then performed to quantify signal intensity in the femoral head and neck. Qualitative assessment of the terminal arterial branches to the femoral head, specifically the inferior retinacular artery (IRA), was also performed. Results. Quantitative MRI revealed a mean reduction of 1.8% (SD 3.1%) of arterial contribution in the femoral head and a mean reduction of 7.1% (SD 10.6%) in the femoral neck in the plating group compared to non-plated controls. Based on femoral head quadrant analysis, the largest mean decrease in arterial contribution was in the inferomedial quadrant (4.0%, SD 6.6%). No significant differences were found between control and experimental hips for any femoral neck or femoral head regions. The inferior retinaculum of Weitbrecht (containing the IRA) was directly visualized in six of 12 specimens. Qualitative MRI assessment confirmed IRA integrity in all specimens. Conclusion. Calcar femoral neck plating at the 6:00 position on the clockface resulted in minimal decrease in femoral head and neck vascularity, and therefore it may be considered as an adjunct to laterally-based fixation for reduction and fixation of femoral neck fractures, especially in younger patients. Cite this article: Bone Jt Open 2021;2(8):611–617

Aims. Increasingly, patients with bilateral hip arthritis wish to undergo staged total hip arthroplasty (THA). With the rise in demand for arthroplasty, perioperative risk assessment and counselling is crucial for shared decision making. However, it is unknown if complications that occur after a unilateral hip arthroplasty predict complications following surgery of the contralateral hip. Patients and Methods. We used nationwide linked discharge data from the Healthcare Cost and Utilization Project between 2005 and 2014 to analyze the incidence and recurrence of complications following the first- and second-stage operations in staged bilateral total hip arthroplasty (BTHAs). Complications included perioperative medical adverse events within 30 to 60 days, and infection and mechanical complications within one year. Conditional probabilities and odds ratios (ORs) were calculated to determine whether experiencing a complication after the first stage of surgery increased the risk of developing the same complication after the second stage. Results. A total of 13 829 patients (5790 men and 8039 women) who underwent staged BTHAs were analyzed. The mean age at first operation was 62.9 years (14 to 95). For eight of the 12 outcomes evaluated, patients who experienced the outcome following the first arthroplasty had a significantly increased probability and odds of developing that same complication following the second arthroplasty, compared with those who did not experience the complication after the first surgery. This was true for digestive complications (OR 25.67, 95% confidence interval (CI) 13.86 to 46.08; p < 0.001), urinary complications (OR 6.48, 95% CI 1.7 to 20.73; p = 0.01), haematoma (OR 12.17, 95% CI 4.55 to 31.14; p < 0.001), deep vein thrombosis (OR 4.82, 95% CI 2.34 to 9.65; p < 0.001), pulmonary embolism (OR 12.03, 95% CI 2.02 to 46.77; p = 0.01), deep hip infection (OR 534.21, 95% CI 314.96 to 909.25; p < 0.001), superficial hip infection (OR 1574.99, 95% CI 269.83 to 9291.81; p < 0.001), and mechanical malfunction (OR 117.49, 95% CI 91.55 to 150.34; p < 0.001). Conclusion. The occurrence of certain complications after unilateral THA is associated with an increased risk of the same complication occurring after staged arthroplasty of the contralateral hip. Patients who experience these complications after unilateral hip arthroplasty should be appropriately counselled regarding their risk profile prior to undergoing staged contralateral hip arthroplasty. Cite this article: Bone Joint J 2019;101-B(6 Supple B):77–83

Objectives. To quantify and compare peri-acetabular bone mineral density (BMD) between a monoblock acetabular component using a metal-on-metal (MoM) bearing and a modular titanium shell with a polyethylene (PE) insert. The secondary outcome was to measure patient-reported clinical function. Methods. A total of 50 patients (25 per group) were randomised to MoM or metal-on-polyethlene (MoP). There were 27 women (11 MoM) and 23 men (14 MoM) with a mean age of 61.6 years (47.7 to 73.2). Measurements of peri-prosthetic acetabular and contralateral hip (covariate) BMD were performed at baseline and at one and two years’ follow-up. The Western Ontario and McMaster Universities osteoarthritis index (WOMAC), University of California, Los Angeles (UCLA) activity score, Harris hip score, and RAND-36 were also completed at these intervals. Results. At two years, only zone 1 showed a loss in BMD (-2.5%) in MoM group compared with a gain in the MoP group (+2.2%). Zone 2 showed loss in both groups (-2.2% for MoM; -3.9% for MoP) and zones 3 and 4 a gain in both groups (+0.1% for MoM; +3.3% for MoP). No other between-group differences were detected. When adjusting for BMD of the contralateral hip, no differences in BMD were observed. The only significant differences in functional scores at two years were higher UCLA activity (7.3 (. sd. 1.2) vs 6.1 (. sd. 1.5); p = 0.01) and RAND-36 physical function (82.1 (. sd. 13.0) vs 64.5 (. sd. 26.4); p = 0.02) for MoM bearings versus MoP. One revision was performed in the MoM group, for aseptic acetabular loosening at 11 months. Conclusions. When controlling for systemic BMD, there were no significant differences between MoM and MoP groups in peri-acetabular BMD. However, increasing reports of adverse tissue reactions with large head MoM THR have restricted the use of the monoblock acetabular component to resurfacing only

There have been several studies examining the association between the morphological characteristics seen in acetabular dysplasia and the incidence of the osteoarthritis (OA). However, most studies focus mainly on acetabular morphological analysis, and few studies have scrutinised the effect of femoral morphology. In this study we enrolled 36 patients with bilateral acetabular dysplasia and early or mid-stage OA in one hip and no OA in the contralateral hip. CT scans were performed from the iliac crest to 2 cm inferior to the tibial tuberosity, and the morphological characteristics of both acetabulum and femur were studied. . In addition, 200 hips in 100 healthy volunteer Chinese adults formed a control group. The results showed that the dysplastic group with OA had a significantly larger femoral neck anteversion and a significantly shorter abductor lever arm than both the dysplastic group without OA and the controls. Femoral neck anteversion had a significant negative correlation with the length of the abductor lever arm and we conclude that it may contribute to the development of OA in dysplastic hips. Cite this article: Bone Joint J 2014; 96-B:1586–93

Aims

Post-traumatic periprosthetic acetabular fractures are rare but serious. Few studies carried out on small cohorts have reported them in the literature. The aim of this work is to describe the specific characteristics of post-traumatic periprosthetic acetabular fractures, and the outcome of their surgical treatment in terms of function and complications.

We investigated the effect of calcitonin in the prevention of acute bone loss after a pertrochanteric fracture and its ability to reduce the incidence of further fractures in the same patient. Fifty women aged between 70 and 80 years who had a pertrochanteric fracture of the hip were randomly allocated to group A (200 IU of nasal salmon calcitonin daily for three months) or group B (placebo). Patients in group A showed a significantly higher level of total alkaline phosphatase and osteocalcin on the 15th day after injury and a significantly higher level of bone alkaline phosphatase on the 90th day after surgery. These patients also had significantly lower levels of urinary C-telopeptide (CrossLaps) on the 15th, 45th and 90th days after injury and lower levels of urinary hydroxyproline on the 15th and 45th days after injury. Patients in group A had significantly higher bone mineral density at all recorded sites except the greater trochanter at three months and one year after operation. After a four-year period of clinical observation, five patients (24%) in group B sustained a new fracture, in four of whom (20%) it was of the contralateral hip. Our findings show that calcitonin reduces acute bone loss in patients with pertrochanteric fractures and may prevent the occurrence of new fractures of the contralateral hip in the elderly

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Pain is the most frequent complaint associated with osteonecrosis of the femoral head (ONFH), but the factors contributing to such pain are poorly understood. This study explored diverse demographic, clinical, radiological, psychological, and neurophysiological factors for their potential contribution to pain in patients with ONFH.

Aims. The aim of this study was to assess the functional gain achieved following hip resurfacing arthroplasty (HRA). Patients and Methods. A total of 28 patients (23 male, five female; mean age, 56 years (25 to 73)) awaiting Birmingham HRA volunteered for this prospective gait study, with an age-matched control group of 26 healthy adults (16 male, ten female; mean age, 56 years (33 to 84)). The Oxford Hip Score (OHS) and gait analysis using an instrumented treadmill were used preoperatively and more than two years postoperatively to measure the functional change attributable to the intervention. Results. The mean OHS improved significantly from 27 to 46 points (p < 0.001) at a mean of 29 months (12 to 60) after HRA. The mean metal ion levels at a mean 32 months (13 to 60) postoperatively were 1.71 (0.77 to 4.83) µg/l (ppb) and 1.77 (0.68 to 4.16) µg/l (ppb) for cobalt and chromium, respectively. When compared with healthy controls, preoperative patients overloaded the contralateral good hip, limping significantly. After HRA, patients walked at high speeds, with symmetrical gait, statistically indistinguishable from healthy controls over almost all characteristics. The control group could only be distinguished by an increased push-off force at higher speeds, which may reflect the operative approach. Conclusion. Patients undergoing HRA improved their preoperative gait pattern of a significant limp to a symmetrical gait at high speeds and on inclines, almost indistinguishable from normal controls. HRA with an approved device offers substantial functional gains, almost indistinguishable from healthy controls. Cite this article: Bone Joint J 2019;101-B:1423–1430

Aims

Metal-on-metal hip resurfacing (MoM-HR) has seen decreased usage due to safety and longevity concerns. Joint registries have highlighted the risks in females, smaller hips, and hip dysplasia. This study aimed to identify if reported risk factors are linked to revision in a long-term follow-up of MoM-HR performed by a non-designer surgeon.

We have compared the biomechanical nature of the reconstruction of the hip in conventional total hip arthroplasty (THA) and surface replacement arthroplasty (SRA) in a randomised study involving 120 patients undergoing unilateral primary hip replacement. The contralateral hip was used as a control. Post-operatively, the femoral offset was significantly increased with THA (mean 5.1 mm; −2.8 to 11.6) and decreased with SRA (mean −3.3 mm; −8.9 to 8.2). Femoral offset was restored within . sd. 4 mm in 14 (25%) of those with THA and in 28 (57%) of the patients receiving SRA (p < 0.001). In the THA group, the leg was lengthened by a mean of 2.6 mm (−6.04 to +12.9), whereas it was shortened by a mean of 1.9 mm (−7.1 to +2.05) in the SRA group, compared with the contralateral side. Leg-length inequality was restored within . sd. 4 mm in 42 (86%) of the SRA and 33 (60%) of the THA patients. The radiological parameters of acetabular reconstruction were similar in both groups. Restoration of the normal proximal femoral anatomy was more precise with SRA. The enhanced stability afforded by the use of a large-diameter femoral head avoided over-lengthening of the limb or increased offset to improve soft-tissue tension as occurs sometimes in THA. In a subgroup of patients with significant pre-operative deformity, restoration of the normal hip anatomy with lower pre-operative femoral offset or significant shortening of the leg was still possible with SRA

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To investigate the extent of bone development around the scaffold of custom triflange acetabular components (CTACs) over time.

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Our primary aim was to assess reoperation-free survival at one year after the index injury in patients aged ≥ 75 years treated with internal fixation (IF) or arthroplasty for undisplaced femoral neck fractures (uFNFs). Secondary outcomes were reoperations and mortality analyzed separately.

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Leg length discrepancy (LLD) is a common pre- and postoperative issue in total hip arthroplasty (THA) patients. The conventional technique for measuring LLD has historically been on a non-weightbearing anteroposterior pelvic radiograph; however, this does not capture many potential sources of LLD. The aim of this study was to determine if long-limb EOS radiology can provide a more reproducible and holistic measurement of LLD.