Aims. To evaluate how abnormal proximal femoral anatomy affects different femoral version measurements in young patients with hip pain. Methods. First, femoral version was measured in 50 hips of symptomatic consecutively selected patients with hip pain (mean age 20 years (SD 6), 60% (n = 25) females) on preoperative CT scans using different measurement methods: Lee et al, Reikerås et al, Tomczak et al, and Murphy et al. Neck-shaft angle (NSA) and α angle were measured on coronal and radial CT images. Second, CT scans from three patients with femoral retroversion, normal femoral version, and anteversion were used to create 3D femur models, which were manipulated to generate models with different NSAs and different cam lesions, resulting in eight models per patient. Femoral version measurements were repeated on manipulated femora. Results. Comparing the different measurement methods for femoral version resulted in a maximum mean difference of 18° (95% CI 16 to 20) between the most proximal (Lee et al) and most distal (Murphy et al) methods. Higher differences in proximal and distal femoral version measurement techniques were seen in femora with greater femoral version (r > 0.46; p < 0.001) and greater NSA (r > 0.37; p = 0.008) between all measurement methods. In the parametric 3D manipulation analysis, differences in femoral version increased 11° and 9° in patients with high and normal femoral version, respectively, with increasing NSA (110° to 150°). Conclusion. Measurement of femoral version angles differ depending on the method used to almost 20°, which is in the range of the aimed surgical correction in derotational femoral osteotomy and thus can be considered clinically relevant. Differences between proximal and distal measurement methods further increase by increasing femoral version and NSA. Measurement methods that take the entire proximal femur into account by using distal landmarks may produce more sensitive measurements of these differences. Cite this article: Bone Jt Open 2022;3(10):759–766

Femoral stem version has a major influence on impingement and early post-operative stability after total hip arthroplasty (THA). The main objective of this study was to evaluate the validity of a novel radiological method for measuring stem version. Anteroposterior (AP) radiographs and three-dimensional CT scans were obtained for 115 patients (female/male 63/72, mean age 62.5 years (50 to 75)) who had undergone minimally invasive, cementless THA. Stem version was calculated from the AP hip radiograph by rotation-based change in the projected prosthetic neck–shaft (NSA*) angle using the mathematical formula ST = arcos [tan (NSA*) / tan (135)]. We used two independent observers who repeated the analysis after a six-week interval. Radiological measurements were compared with 3D-CT measurements by an independent, blinded external institute. We found a mean difference of 1.2° (. sd. 6.2) between radiological and 3D-CT measurements of stem version. The correlation between the mean radiological and 3D-CT stem torsion was r = 0.88 (p < 0.001). The intra- (intraclass correlation coefficient ≥ 0.94) and inter-observer agreement (mean concordance correlation coefficient = 0.87) for the radiological measurements were excellent. We found that femoral tilt was associated with the mean radiological measurement error (r = 0.22, p = 0.02). . The projected neck–shaft angle is a reliable method for measuring stem version on AP radiographs of the hip after a THA. However, a highly standardised radiological technique is required for its precise measurement. . Cite this article: Bone Joint J 2015; 97-B:306–11

Version of the femoral stem is an important factor influencing the risk of dislocation after total hip replacement (THR) as well as the position of the acetabular component. However, there is no radiological method of measuring stem anteversion described in the literature. We propose a radiological method to measure stem version and have assessed its reliability and validity. In 36 patients who underwent THR, a hip radiograph and CT scan were taken to measure stem anteversion. The radiograph was a modified Budin view. This is taken as a posteroanterior radiograph in the sitting position with 90° hip flexion and 90° knee flexion and 30° hip abduction. The angle between the stem-neck axis and the posterior intercondylar line was measured by three independent examiners. The intra- and interobserver reliabilities of each measurement were examined. The radiological measurements were compared with the CT measurements to evaluate their validity. The mean radiological measurement was 13.36° (sd 6.46) and the mean CT measurement was 12.35° (sd 6.39) (p = 0.096). The intra- and interobserver reliabilities were excellent for both measurements. The radiological measurements correlated well with the CT measurements (p = 0.001, r = 0.877). The modified Budin method appears reliable and valid for the measurement of femoral stem anteversion.

Cite this article: Bone Joint J 2013;95-B:877–80.

Aims. Although CT is considered the benchmark to measure femoral version, 3D biplanar radiography (hipEOS) has recently emerged as a possible alternative with reduced exposure to ionizing radiation and shorter examination time. The aim of our study was to evaluate femoral stem version in postoperative total hip arthroplasty (THA) patients and compare the accuracy of hipEOS to CT. We hypothesize that there will be no significant difference in calculated femoral stem version measurements between the two imaging methods. Methods. In this study, 45 patients who underwent THA between February 2016 and February 2020 and had both a postoperative CT and EOS scan were included for evaluation. A fellowship-trained musculoskeletal radiologist and radiological technician measured femoral version for CT and 3D EOS, respectively. Comparison of values for each imaging modality were assessed for statistical significance. Results. Comparison of the mean postoperative femoral stem version measurements between CT and 3D hipEOS showed no significant difference (p = 0.862). In addition, the two version measurements were strongly correlated (r = 0.95; p < 0.001), and the mean paired difference in postoperative femoral version for CT scan and 3D biplanar radiography was -0.09° (95% confidence interval -1.09 to 0.91). Only three stem measurements (6.7%) were considered outliers with a > 5° difference. Conclusion. Our study supports the use of low-dose biplanar radiography for the postoperative assessment of femoral stem version after THA, demonstrating high correlation with CT. We found no significant difference for postoperative femoral version when comparing CT to 3D EOS. We believe 3D EOS is a reliable option to measure postoperative femoral version given its advantages of lower radiation dosage and shorter examination time. Cite this article: Bone Joint J 2022;104-B(11):1196–1201

Aims. Periacetabular osteotomy (PAO) is an established treatment for acetabular dysplasia. It has also been proposed as a treatment for patients with acetabular retroversion. By reviewing a large cohort, we aimed to test whether outcome is equivalent for both types of morphology and identify factors that influenced outcome. Methods. A single-centre, retrospective cohort study was performed on patients with acetabular retroversion treated with PAO (n = 62 hips). Acetabular retroversion was diagnosed clinically and radiologically (presence of a crossover sign, posterior wall sign, lateral centre-edge angle (LCEA) between 20° and 35°). Outcomes were compared with a control group of patients undergoing PAO for dysplasia (LCEA < 20°; n = 86 hips). Femoral version was recorded. Patient-reported outcome measures (PROMs), complications, and reoperation rates were measured. Results. The mean Non-Arthritic Hip Score (NAHS) preoperatively was 58.6 (SD 16.1) for the dysplastic hips and 52.5 (SD 12.7) for the retroverted hips (p = 0.145). Postoperatively, mean NAHS was 83.0 (SD 16.9) and 76.7 (SD 17.9) for dysplastic and retroverted hips respectively (p = 0.041). Difference between pre- and postoperative NAHS was slightly lower in the retroverted hips (18.3 (SD 22.1)) compared to the dysplastic hips (25.2 (SD 15.2); p = 0.230). At mean 3.5 years’ follow-up (SD 1.9), one hip needed a revision PAO and no hips were converted to total hip arthroplasty (THA) in the retroversion group. In the control group, six hips (7.0%) were revised to THA. No differences in complications (p = 0.106) or in reoperation rate (p = 0.087) were seen. Negative predictors of outcome for patients undergoing surgery for retroversion were female sex, obesity, hypermobility, and severely decreased femoral anteversion. Conclusion. A PAO is an effective surgical intervention for acetabular retroversion and produces similar improvements when used to treat dysplasia. Femoral version should be routinely assessed in these patients and when extremely low (< 0°), as an additional procedure to address this abnormality may be necessary. Females with signs of hypermobility should also be consulted of the likely guarded improvement. Cite this article: Bone Jt Open 2021;2(9):757–764

Aims. The frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes. Methods. A retrospective institutional review board-approved observational study was performed with 333 symptomatic patients (384 hips) with hip pain due to FAI evaluated for hip preservation surgery. Overall, 142 patients (165 hips) had cam-type FAI, while 118 patients (137 hips) had mixed-type FAI. The allocation to each subgroup was based on reference values calculated on anteroposterior radiographs. CT/MRI-based measurement of FV (Murphy method) and AV were retrospectively compared among five FAI subgroups. Frequency of decreased FV < 10°, severely decreased FV < 5°, and absolute femoral retroversion (FV < 0°) was analyzed. Results. A significantly (p < 0.001) lower mean FV was found in patients with cam-type FAI (15° (SD 10°)), and in patients with mixed-type FAI (17° (SD 11°)) compared to severe over-coverage (20° (SD 12°). Frequency of decreased FV < 10° was significantly (p < 0.001) higher in patients with cam-type FAI (28%, 46 hips) and in patients with over-coverage (29%, 11 hips) compared to severe over-coverage (12%, 5 hips). Absolute femoral retroversion (FV < 0°) was found in 13% (5 hips) of patients with over-coverage, 6% (10 hips) of patients with cam-type FAI, and 5% (7 hips) of patients with mixed-type FAI. The frequency of decreased FV< 10° combined with acetabular retroversion (AV < 10°) was 6% (8 hips) in patients with mixed-type FAI and 5% (20 hips) in all FAI patients. Of patients with over-coverage, 11% (4 hips) had decreased FV < 10° combined with acetabular retroversion (AV < 10°). Conclusion. Patients with cam-type FAI had a considerable proportion (28%) of decreased FV < 10° and 6% had absolute femoral retroversion (FV < 0°), even more for patients with pincer-type FAI due to over-coverage (29% and 13%). This could be important for patients evaluated for open hip preservation surgery or hip arthroscopy, and each patient requires careful personalized evaluation. Cite this article: Bone Jt Open 2022;3(7):557–565

Aims. This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD. Methods. We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology. Results. The mean follow-up was 96 months (67 to 139). The SHV, mHHS, WOMAC, and Tegner scores significantly improved (p < 0.001) at last follow-up. According to SHV and mHHS, there were three hips (7%) with poor results (SHV < 70), three (7%) with a fair score (70 to 79), eight (19%) with good results (80 to 89), and 28 (67%) who scored excellent (> 90) at the last follow-up. There were 11 subsequent operations: nine implant removals due to local irritation, one resection of postoperative heterotopic ossification, and one hip arthroscopy for intra-articular adhesions. No hips were converted to total hip arthroplasty at last follow-up. The presence of preoperative labral lesions or LT lesions did not influence any PROMs at last follow-up. From the three hips that had poor PROMs, two have developed severe osteoarthritis (> Tönnis II), presumably due to surgical overcorrection (postoperative AI < -10°). Conclusion. PAO is reliable in treating BHD with favourable mid-term outcomes. Concomitant LT and labral lesions did not negatively influence outcomes in our cohort. Technical accuracy with avoidance of overcorrection is essential in achieving successful outcomes. Cite this article: Bone Joint J 2023;105-B(7):735–742

We measured the orientation of the acetabular and femoral components in 45 patients (33 men, 12 women) with a mean age of 53.4 years (30 to 74) who had undergone revision of metal-on-metal hip resurfacings. Three-dimensional CT was used to measure the inclination and version of the acetabular component, femoral version and the horizontal femoral offset, and the linear wear of the removed acetabular components was measured using a roundness machine. We found that acetabular version and combined version of the acetabular and femoral components were weakly positively correlated with the rate of wear. The acetabular inclination angle was strongly positively correlated with the rate of wear. Femoral version was weakly negatively correlated with the rate of wear. Application of a threshold of > 5 μm/year for the rate of wear in order to separate the revisions into low or high wearing groups showed that more high wearing components were implanted outside Lewinnek’s safe zone, but that this was mainly due to the inclination of the acetabular component, which was the only parameter that significantly differed between the groups. We were unable to show that excess version of the acetabular component alone or combined with femoral version was associated with an increase in the rate of wear based on our assessment of version using CT

Objectives. The spinopelvic relationship (including pelvic incidence) has been shown to influence pelvic orientation, but its potential association with femoroacetabular impingement has not been thoroughly explored. The purpose of this study was to prove the hypothesis that decreasing pelvic incidence is associated with increased risk of cam morphology. Methods. Two matching cohorts were created from a collection of cadaveric specimens with known pelvic incidences: 50 subjects with the highest pelvic incidence (all subjects > 60°) and 50 subjects with the lowest pelvic incidence (all subjects < 35°). Femoral version, acetabular version, and alpha angles were directly measured from each specimen bilaterally. Cam morphology was defined as alpha angle > 55°. Differences between the two cohorts were analysed with a Student’s t-test and the difference in incidence of cam morphology was assessed using a chi-squared test. The significance level for all tests was set at p < 0.05. Results. Cam morphology was identified in 47/100 (47%) femurs in the cohort with pelvic incidence < 35° and in only 25/100 (25%) femurs in the cohort with pelvic incidence > 60° (p = 0.002). The mean alpha angle was also greater in the cohort with pelvic incidence < 35° (mean 53.7°, . sd. 10.7° versus mean 49.7°, . sd. 10.6°; p = 0.008). Conclusions. Decreased pelvic incidence is associated with development of cam morphology. We propose a novel theory wherein subjects with decreased pelvic incidence compensate during gait (to maintain optimal sagittal balance) through anterior pelvic tilt, creating artificial anterior acetabular overcoverage and recurrent impingement that increases risk for cam morphology. Cite this article: W. Z. Morris, C. A. Fowers, R. T. Yuh, J. J. Gebhart, M. J. Salata, R. W. Liu. Decreasing pelvic incidence is associated with greater risk of cam morphology. Bone Joint Res 2016;5:387–392. DOI: 10.1302/2046-3758.59.BJR-2016-0028.R1

If a surgeon is faced with altered lesser trochanter anatomy when revising the femoral component in revision total hip replacement, a peri-prosthetic fracture, or Paprosky type IIIb or type IV femoral bone loss, a modular tapered stem offers the advantages of accurately controlling femoral version and length. The splines of the taper allow rotational control, and improve the fit in femoral canals with diaphyseal bone loss. In general, two centimetres of diaphyseal contact is all that is needed to gain stability with modular tapered stems. By allowing the proximal body trial to rotate on a well-fixed distal segment during trial reduction, appropriate anteversion can be obtained in order to improve intra-operative stability, and decrease the dislocation risk. However, modular stems should not be used for all femoral revisions, as implant fracture and corrosion at modular junctions can still occur. Cite this article: Bone Joint J 2013;95-B, Supple A:95–7

Aims

Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients.

Aims

Pelvic tilt is believed to affect the symptomology of osteoarthritis (OA) of the hip by alterations in joint movement, dysplasia of the hip by modification of acetabular cover, and femoroacetabular impingement by influencing the impingement-free range of motion. While the apparent role of pelvic tilt in hip pathology has been reported, the exact effects of many forms of treatment on pelvic tilt are unknown. The primary aim of this study was to investigate the effects of surgery on pelvic tilt in these three groups of patients.

Aims

Precise implant positioning, tailored to individual spinopelvic biomechanics and phenotype, is paramount for stability in total hip arthroplasty (THA). Despite a few studies on instability prediction, there is a notable gap in research utilizing artificial intelligence (AI). The objective of our pilot study was to evaluate the feasibility of developing an AI algorithm tailored to individual spinopelvic mechanics and patient phenotype for predicting impingement.

Aims

Hip arthroscopy has gained prominence as a primary surgical intervention for symptomatic femoroacetabular impingement (FAI). This study aimed to identify radiological features, and their combinations, that predict the outcome of hip arthroscopy for FAI.

Aims

The aim of this study is to evaluate whether acetabular retroversion (AR) represents a structural anatomical abnormality of the pelvis or is a functional phenomenon of pelvic positioning in the sagittal plane, and to what extent the changes that result from patient-specific functional position affect the extent of AR.

Aims

Achieving accurate implant positioning and restoring native hip biomechanics are key surgeon-controlled technical objectives in total hip arthroplasty (THA). The primary objective of this study was to compare the reproducibility of the planned preoperative centre of hip rotation (COR) in patients undergoing robotic arm-assisted THA versus conventional THA.

Aims

The lateral centre-edge angle (LCEA) is a plain radiological measure of superolateral cover of the femoral head. This study aims to establish the correlation between 2D radiological and 3D CT measurements of acetabular morphology, and to describe the relationship between LCEA and femoral head cover (FHC).

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.

Aims

Pelvic tilt (PT) can significantly change the functional orientation of the acetabular component and may differ markedly between patients undergoing total hip arthroplasty (THA). Patients with stiff spines who have little change in PT are considered at high risk for instability following THA. Femoral component position also contributes to the limits of impingement-free range of motion (ROM), but has been less studied. Little is known about the impact of combined anteversion on risk of impingement with changing pelvic position.

Aims

Patients with spinal pathology who undergo total hip arthroplasty (THA) have an increased risk of dislocation and revision. The aim of this study was to determine if the use of the Hip-Spine Classification system in these patients would result in a decreased rate of postoperative dislocation in patients with spinal pathology.