Introduction. Ceramic heads are used in hip revision surgery to mitigate corrosion concerns. Manufacturers recommend using a pristine titanium sleeve in conjunction with a well-fixed metal stem to prevent early failure of the ceramic head. However, the influence of impact force, head size, and sleeve offset on pull-off strength and seating displacement of a revision head assembly is not fully understood. Therefore, the purpose of this study was to investigate the pull-off strength and displacement of commercially available revision ceramic heads and titanium taper sleeve offsets (BIOLOX OPTION, CeramTec GmbH, Plochingen, Germany) while covering a range of clinically relevant impaction forces. Methods. Two head sizes (28 mm, n = 12 and 36 mm, n = 12) and two taper adapter sleeve offsets (small, n = 12 and extra-large, n = 12) were tested in this study. A dynamic impaction rig was constructed to seat the head, sleeve, and stem assembly (Fig. 1). Consistent impaction forces were achieved by dropping a hammer fixed to a lever arm from a pre-determined height onto a standard impactor instrumented with a piezoelectric force sensor (PCB Piezotronics Inc.). Axially applied forces of 2 kN and 6 kN were used to cover a range of typical impaction forces. Three non-contact differential variable reluctance transducers (LORD Sensing Systems) were used to track the displacement of the head relative to the stem. Subsequently, samples were transferred to a servo hydraulic testing machine, and a pull-off test was carried out per ISO 7206–10 to measure the disassembly force. Results. For all head and sleeve combinations assembled at 6 kN, pull-off forces and assembly displacements were over two times the values measured at 2 kN. As expected, an increased assembly force resulted in increased pull-offs and displacements. Head size did not play a significant role on measured outcomes. Regarding sleeve offsets, at assembly of 6 kN mean pull-off forces for extra-large sleeves were reduced by approximately 25% relative to small sleeves (Fig 2). However, at a 2 kN assembly, sleeve offsets did not appear to influence pull-off forces. Discussion. This study assessed the effect of impact assembly force, head size, and sleeve offset on pull-off strength and seating displacement of revision ceramic heads. The data suggests assembly force and sleeve offset may influence the pull-off strength and seating displacement of modular heads used in revision hip arthroplasty. Mean pull-off forces for revision heads were comparable in magnitude and trend to previous studies assessing the linear relationship between assembly force and pull-off force in primary heads (Krull et al., 2017, Rehmer et al., 2012). Lower pull-off forces were observed for extra-large sleeves when compared to small sleeves, indicating, decreased contact at the sleeve and stem interface for extra-large offsets may play a role in reducing pull-off forces. Acknowledgment:. The authors would like to thank CeramTec GmbH (Plochingen, Germany) for providing the head, sleeve, and stem implants. For any figures or tables, please contact authors directly

We report an unusual complication of late dislocation of a total hip replacement. The femoral stem had completely migrated from the shaft. The insertion of a new long-stem prosthesis was successful.

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

Securing the osteotomized greater trochanter (GT) during total hip arthroplasty (THA) for dislocated dysplastic hips (DDH) poses a significant challenge. This study evaluates the union rate and effectiveness of a 2-strand transverse wiring technique utilizing the lesser trochanter for wire anchorage and tensioning. A digastric anterior slide trochanteric osteotomy was performed in 106 patients (118 hips) undergoing THA for DDH. Following uncemented stem insertion, the GT was transferred and fixed to the lateral cortex of the proximal femur using monofilament stainless steel wires. In 72 out of 106 patients (80 hips), the GT was fixed with 2 transverse wire cerclages threaded through 2 drill holes in the base of the lesser trochanter, spaced vertically 5–10 millimeters apart. The wires were wrapped transversely over the GT and tightened, avoiding contact with its tendinous attachments. Patients were regularly monitored, and GT union was assessed clinically and radiographically. Patient ages ranged from 20 to 57 years (mean 35.5), with a follow-up period ranging from 1.5 to 12 years (mean 6.2). The mean union time was 3.3 months (range 2–7). Among all hips, two developed stable nonunion and single wire breakage, but no fragment displacement (2.5%). Two hips exhibited delayed union, eventually healing at 6 and 7 months after surgery. Reattachment of the greater trochanter utilizing a 2-strand transverse wire cerclage anchored at the base of the lesser trochanter demonstrated a high rate of union (97.5%) following THA in dislocated DDH cases

The painful hip without obvious clinical or radiographic signs of complications is a well-known scenario for surgeons. The clinical tools we have access to currently lack a dynamic test for detecting early signs of motion between implant and bone. A new software, Sectra IMA, has a potential to facilitate diagnosis of early implant loosening by analysis of paired CT exams. In clinical practise the two scans are acquired by endpoint of a possible motion, “a provocation CT”, for example maximal external and internal rotation in a CT hip examination. 20 years of research by Olivecrona and Weidenhielm is the scientific background for the technique. Early results are presented by Sandberg et al 2022. To further validate and create clinical evidence more extensive clinical studies is needed. A proposal for a multicentric, global clinical study will be presented for further discussion. A new technique for diagnosis of acetabular cup loosening using computed tomography: preliminary experience in 10 patients. Henrik Olivecrona, Lotta Olivecrona, Lars Weidenhielm, Marilyn E Noz, Jocelyn Kardos, Gerald Q Maguire Jr, Michael P Zeleznik, Peter Aspelin. Acta Orthop. 2008 Jun;79(3):346-53. doi: 10.1080/17453670710015247. Inducible displacement CT increases the diagnostic accuracy of aseptic loosening in primary total hip arthroplasty. Sandberg O, Carlsson S, Harbom E, Cappelen V, Tholén S, Olivecrona H, Wretenberg P. Acta Orthop. 2022 Oct 31;93:831-836. doi: 10.2340/17453674.2022.5240.PMID: 36314542

Aims. One goal of total hip arthroplasty is to restore normal hip anatomy. The aim of this study was to compare displacement of the centre of rotation (COR) using a standard reaming technique with a technique in which the acetabulum was reamed immediately peripherally and referenced off the rim. Patients and Methods. In the first cohort the acetabulum was reamed to the floor followed by sequentially larger reamers. In the second cohort the acetabulum was only reamed peripherally, starting with a reamer the same size as the native femoral head. Anteroposterior pelvic radiographs were analysed for acetabular floor depth and vertical and horizontal position of the COR. Results. Horizontally, the mean medial displacement of the COR was 0.8 mm (standard deviation (. sd. ) 1.4) in the peripheral remaing group and 5.0 mm (. sd. 3.30) in the standard reaming group (p < 0.001). Vertically, the mean superior displacement of the COR was 0.7 mm (. sd. 1.3) in the peripheral reaming group and 3.7 mm (. sd. 2.6) in the standard reaming group (p <  0.001). In the standard reaming group, there was a strong correlation between the pre-operative acetabular floor depth and displacement of the COR (p < 0.001). Conclusion. Reaming the acetabulum to the floor can lead to significant displacement of the COR medially and superiorly. This displacement is related to the pre-operative acetabular floor depth and cannot always be compensated by using a high offset stem. Cite this article: Bone Joint J 2016;98-B:1597–603

Background. Trochanteric fractures account for up to 20% of all periprosthetic fractures occurring during or after total hip arthroplasties (THAs). They are frequently managed conservatively except in cases with significant displacement. There is a paucity of literature describing the indications and results of operative or non-operative management of these fractures. Methods. 173 trochanteric fractures occurred in 171 patients, after all primary THAs performed from 1989–2017. Mean age at fracture was 64-years, with 65% being female. Mean follow-up was 7.6-years. Patient's radiographs and Harris Hip Scores (HHS) were recorded. There were 85 (49%) intraoperative and 88 postoperative fractures. Mean time from THA to fracture was 66 months for the postoperative group. 79 (46%) cases were fixed (68 intraoperative, 11 postoperative). Fixation was considered at the discretion of the surgeon. Within the 88 postoperative fractures, 30 were associated with polyethylene wear and osteolysis. 77 were initially treated conservatively and 11 were immediately fixed (8 revisions due to osteolysis, and 3 fracture fixations due to disability associated to displacement >1cm). 19 of the 30 postoperative fractures associated with polyethylene wear and osteolysis, eventually underwent revision. Results. Trochanteric union rate was 45% in the non-operative group, and 86% in the operative group (p<0.01). No patient undergoing trochanteric fracture fixation required fixation revision; however the reoperation rate for painful hardware was 6.3%. The non-operative group required unplanned fracture fixation in 3 cases: 2 associated to instability; and 1 due to pain, and displacement >1cm. The median HHS at last follow-up significantly improved when comparing the fixation and non-fixation groups (90 vs 81.5, respectively. p=0.02). Conclusions. Trochanteric fracture operative management was associated with high union rates and improved functional outcomes. When possible, intraoperative fractures should be treated with fixation; postoperative fractures were commonly treated non-operatively except in cases with osteolysis, instability or displacement greater >1cm. Summary. Operative management of periprosthetic trochanteric fractures resulted in increased fracture union rates and it improved functional outcomes. For any tables or figures, please contact the authors directly

Aims. The processes linking long-term bisphosphonate treatment to atypical fracture remain elusive. To establish a means of exploring this link, we have examined how long-term bisphosphonate treatment with prior ovariectomy modifies femur fracture behaviour and tibia mass and shape in murine bones. Methods. Three groups (seven per group) of 12-week-old mice were: 1) ovariectomized and 20 weeks thereafter treated weekly for 24 weeks with 100 μm/kg subcutaneous ibandronate (OVX+IBN); 2) ovariectomized (OVX); or 3) sham-operated (SHAM). Quantitative fracture analysis generated biomechanical properties for the femoral neck. Tibiae were microCT scanned and trabecular (proximal metaphysis) and cortical parameters along almost its whole length measured. Results. Fracture analyses revealed that OVX+IBN significantly reduced yield displacement (vs SHAM/OVX) and resilience, and increased stiffness (vs SHAM). OVX+IBN elevated tibial trabecular parameters and also increased cortical cross-sectional area and second moment of area around minor axis, and diminished ellipticity proximally. Conclusion. These data indicate that combined ovariectomy and bisphosphonate generates cortical changes linked with greater bone brittleness and modified fracture characteristics, which may provide a basis in mice for interrogating the mechanisms and genetics of atypical fracture aetiology. Cite this article: Bone Joint Open 2020;1-9:512–519

Aims. Our retrospective analysis reports the outcome of patients operated for slipped capital femoral epiphysis using the modified Dunn procedure. Results, complications, and the need for revision surgery are compared with the recent literature. Methods. We retrospectively evaluated 17 patients (18 hips) who underwent the modified Dunn procedure for the treatment of slipped capital femoral epiphysis. Outcome measurement included standardized scores. Clinical assessment included ambulation, leg length discrepancy, and hip mobility. Radiographically, the quality of epiphyseal reduction was evaluated using the Southwick and Alpha-angles. Avascular necrosis, heterotopic ossifications, and osteoarthritis were documented at follow-up. Results. At a mean follow-up of more than nine years, the mean modified Harris Hip score was 88.7 points, the Hip Disability and Osteoarthritis Outcome Score (HOOS) 87.4 , the Merle d’Aubigné Score 16.5 points, and the UCLA Activity Score 8.4. One patient developed a partial avascular necrosis of the femoral head, and one patient already had an avascular necrosis at the time of delayed diagnosis. Two hips developed osteoarthritic signs at 14 and 16 years after the index operation. Six patients needed a total of nine revision surgeries. One operation was needed for postoperative hip subluxation, one for secondary displacement and implant failure, two for late femoroacetabular impingement, one for femoroacetabular impingement of the opposite hip, and four for implant removal. Conclusion. Our series shows good results and is comparable to previous published studies. The modified Dunn procedure allows the anatomic repositioning of the slipped epiphysis. Long-term results with subjective and objective hip function are superior, avascular necrosis and development of osteoarthritis inferior to other reported treatment modalities. Nevertheless, the procedure is technically demanding and revision surgery for secondary femoroacetabular impingement and implant removal are frequent. Cite this article: 2020;1-4:80–87

There is a strong association between the presence of a calcar collar on a cementless stem and a reduced risk of revision surgery for periprosthetic fracture of the femur (PFF). A medial calcar collar may act to reduce relative movement between the implant and femur during PFF, through calcar-collar contact (CCC). The aims were:. Estimate the effect of CCC on periprosthetic fracture mechanics. Estimate the effect of initial calcar-collar separation on the likelihood of CCC. Three groups of six composite femurs were implanted with a fully coated collared cementless femoral stem. Neck resection differed between groups (group 1 = no additional resection, group 2 = 3mm additional resection, group 3 = 6mm additional resection). PFF were simulated using a previously published technique. Fracture torque and rotational displacement were measured and torsional stiffness and rotational work prior to fracture were estimated. Results between trials where CCC did and did not occur where compared using Mann-Whitney U tests. Logistic regression estimated the odds (OR) of failing with 95% confidence interval (CI) to achieve CCC for a given initial separation. Where CCC occurred fracture torque was greater (47.33 [41.03 to 50.45] Nm versus 38.26 [33.70 to 43.60] Nm, p= 0.05) and torsional stiffness was greater (151.38 [123.04 to 160.42] rad.Nm. −1. versus 96.86 [84.65 to 112.98] rad.Nm. −1. , p <0.01). CCC was occurred in all cases in group one, 50% in group two and 0% in group three. OR of failure to obtain CCC increased 3.8 fold (95% CI 1.6 to 30.2, p <0.05) for each millimetre of separation. Resistance to fracture and construct stiffness increased when a the collar made contact with the calcar prior to fracture and the chances of contact decrease with increasing initial separation at the time of implantation. Surgeons should aim to achieve a calcar-collar distance of less than 1mm following implantation to ensure CCC and to reduce the risk of fracture

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.

Objectives. Osteosynthesis of anterior pubic ramus fractures using one large-diameter screw can be challenging in terms of both surgical procedure and fixation stability. Small-fragment screws have the advantage of following the pelvic cortex and being more flexible. The aim of the present study was to biomechanically compare retrograde intramedullary fixation of the superior pubic ramus using either one large- or two small-diameter screws. Materials and Methods. A total of 12 human cadaveric hemipelvises were analysed in a matched pair study design. Bone mineral density of the specimens was 68 mgHA/cm. 3. (standard deviation (. sd). 52). The anterior pelvic ring fracture was fixed with either one 7.3 mm cannulated screw (Group 1) or two 3.5 mm pelvic cortex screws (Group 2). Progressively increasing cyclic axial loading was applied through the acetabulum. Relative movements in terms of interfragmentary displacement and gap angle at the fracture site were evaluated by means of optical movement tracking. The Wilcoxon signed-rank test was applied to identify significant differences between the groups. Results. Initial axial construct stiffness was not significantly different between the groups (p = 0.463). Interfragmentary displacement and gap angle at the fracture site were also not statistically significantly different between the groups throughout the evaluated cycles (p ⩾ 0.249). Similarly, cycles to failure were not statistically different between Group 1 (8438, . sd. 6968) and Group 2 (10 213, . sd. 10 334), p = 0.379. Failure mode in both groups was characterised by screw cutting through the cancellous bone. Conclusion. From a biomechanical point of view, pubic ramus stabilisation with either one large or two small fragment screw osteosynthesis is comparable in osteoporotic bone. However, the two-screw fixation technique is less demanding as the smaller screws deflect at the cortical margins. Cite this article: Y. P. Acklin, I. Zderic, S. Grechenig, R. G. Richards, P. Schmitz, B. Gueorguiev. Are two retrograde 3.5 mm screws superior to one 7.3 mm screw for anterior pelvic ring fixation in bones with low bone mineral density? Bone Joint Res 2017;6:8–13. DOI: 10.1302/2046-3758.61.BJR-2016-0261

Introduction. The periacetabular osteotomy (PAO) improves hip joint mechanics in patients with symptomatic dysplasia. As a consequence of the multi-planar acetabular re-orientation, the course of the iliopsoas tendon over the hip may be affected, potentially resulting in iliopsoas tendon-related pain. At present, little information regarding the incidence of iliopsoas-related pathology following PAO exists. We aimed to identify the incidence of iliopsoas-related pain following PAO. Secondarily, we aimed to identify any risk factors associated with this pathology. Methods. We retrospectively reviewed the PAO's performed from 2014–2017, for symptomatic dysplasia in our unit (single-surgeon, minimum 1-year follow-up). All patients with adequate pelvic radiographs were included. Radiographic parameters of dysplasia were measured from pre- and post-operative AP pelvic radiographs using a validated software (SHIPS). 1. The degree of pubis displacement was classified according to our novel system. Cases were defined as those with evidence of iliopsoas-related pain post PAO (positive response to iliopsoas tendon-sheath steroid/local anaesthetic injection). Results. A total of 241 patients were included (mean age 28 years). We identified 23 cases (10.6%) with iliopsoas tendon-related pain post-PAO. Three of these cases required an open iliopsoas tendon release and 1 required a revision of their PAO. This was successful in treating symptoms in all. The remainder required either 1–2 iliopsoas tendon-sheath steroid injections to successfully treat their symptoms. We found no significantly associated risk factors with regard to demographics, severity or type of dysplasia, and degree of pubis displacement. Conclusion. The minimally-invasive PAO remains a successful technique for treating symptomatic dysplasia. Despite this, we report a 10.6% incidence of iliopsoas tendon-related pain following surgery. In the vast majority this is successfully treated with an iliopsoas tendon-sheath steroid injection. The ability to identify and treat patients with this pathology early during their post-operative PAO recovery will enable patients to maximise their rehabilitation outcomes

Aims

The objectives of this study were to investigate the patient characteristics and mortality of Vancouver type B periprosthetic femoral fractures (PFF) subgroups divided into two groups according to femoral component stability and to compare postoperative clinical outcomes according to treatment in Vancouver type B2 and B3 fractures.

Aims. The aim of this study was to report the long-term results of rotational acetabular osteotomy (RAO) for symptomatic hip dysplasia in patients aged younger than 21 years at the time of surgery. Patients and Methods. We evaluated 31 patients (37 hips) aged younger than 21 years at the time of surgery retrospectively. There were 29 female and two male patients. Their mean age at the time of surgery was 17.4 years (12 to 21). The mean follow-up was 17.9 years (7 to 30). The RAO was combined with a varus or valgus femoral osteotomy or a greater trochanteric displacement in eight hips, as instability or congruence of the hip could not be corrected adequately using RAO alone. Results. The mean Merle d’Aubigné clinical score improved significantly from 15.4 to 17.2 (p < 0.0001). The mean centre-edge (CE) angle improved from -2.6° to 26°, the mean acetabular roof angle improved from 3.0° to 5.2°, and the mean head lateralization index improved from 0.68 to 0.62. Progression of radiological osteoarthritis (OA) was seen in seven hips, but no patient underwent total hip arthroplasty. Conclusion. RAO is an effective form of correction for a severely dysplastic hip in adolescent and young adult patients. Cite this article: Bone Joint J 2019;101-B:390–395

Aims

To develop prediction models using machine-learning (ML) algorithms for 90-day and one-year mortality prediction in femoral neck fracture (FNF) patients aged 50 years or older based on the Hip fracture Evaluation with Alternatives of Total Hip arthroplasty versus Hemiarthroplasty (HEALTH) and Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trials.

Aims. Despite few good-quality studies on the subject, total hip arthroplasty (THA) is increasingly being performed for displaced intracapsular fractures of the neck of femur. We compared outcomes of all patients with displacement of these fractures treated surgically over a ten-year period in one institution. Methods. A total of 2,721 patients with intracapsular fractures of the femoral neck treated with either a cemented hemiarthroplasty or a THA at a single centre were retrospectively reviewed. The primary outcomes analyzed were readmission for any reason and revision surgery. We secondarily looked at mortality rates. Results. We found no difference in the overall revision rate or rate of infection. However, the rates of readmission due to dislocation, pain, and trochanteric bursitis were significantly higher in the THA group (p = 0.001, p < 0.001, p < 0.001, and p = 0.001, respectively). Conclusion. Our study, comparing the outcomes of neck of femur fractures treated with a cemented hemiarthroplasty and THA, revealed the perceived superiority of THA was not borne out by our results. This should be carefully considered before any radical change in practice regarding the use of THA for displaced intracapsular fractures of the femoral neck. Cite this article: Bone Joint J 2020;102-B(6):693–698

The modified Smith–Petersen and Kocher–Langenbeck approaches were used to expose the lateral cutaneous nerve of the thigh and the femoral, obturator and sciatic nerves in order to study the risk of injury to these structures during the dissection, osteotomy, and acetabular reorientation stages of a Bernese peri-acetabular osteotomy. Injury of the lateral cutaneous nerve of thigh was less likely to occur if an osteotomy of the anterior superior iliac spine had been carried out before exposing the hip. The obturator nerve was likely to be injured during unprotected osteotomy of the pubis if the far cortex was penetrated by > 5 mm. This could be avoided by inclining the osteotome 45° medially and performing the osteotomy at least 2 cm medial to the iliopectineal eminence. . The sciatic nerve could be injured during the first and last stages of the osteotomy if the osteotome perforated the lateral cortex of ischium and the ilio-ischial junction by > 10 mm. The femoral nerve could be stretched or entrapped during osteotomy of the pubis if there was significant rotational or linear displacement of the acetabulum. Anterior or medial displacement of < 2 cm and lateral tilt (retroversion) of < 30° were safe margins. The combination of retroversion and anterior displacement could increase tension on the nerve. Strict observation of anatomical details, proper handling of the osteotomes and careful manipulation of the acetabular fragment reduce the neurological complications of Bernese peri-acetabular osteotomy. Cite this article: Bone Joint J 2015;97-B:636–41

Aims

Periprosthetic fracture and implant loosening are two of the major reasons for revision surgery of cementless implants. Optimal implant fixation with minimal bone damage is challenging in this procedure. This pilot study investigates whether vibratory implant insertion is gentler compared to consecutive single blows for acetabular component implantation in a surrogate polyurethane (PU) model.

Aims

To describe the epidemiology of acetabular fractures including patient characteristics, injury mechanisms, fracture patterns, treatment, and mortality.