Total hip arthroplasty is well established as a successful treatment modality for end stage arthritis, with a variety of components currently available. However, utilising traditional stemmed implants in patients with distorted proximal femoral geometry can be technically challenging with increased risk of complications. We present seven patients with distorted proximal femoral anatomy or failed hip arthroplasty in whom a technically challenging primary or revision operation was simplified by use of a Proxima stem. This is a short, stemless, metaphyseal loading implant with a pronounced lateral flare. At twelve months follow up there have been no complications with average improvement in Oxford and Harris scores of forty and forty-nine respectively. Radiological analysis shows all stems to be stable and well fixed. Designed primarily as a bone conserving implant for primary hip arthroplasty we propose that the Proxima prosthesis also be considered in cases where a conventional stemmed implant may not be suitable due to challenging proximal femoral anatomy. The use of the stemless Proxima implant provided a simple solution in seven difficult and potentially lengthy complex primary and revision hip arthroplasties with gratifying clinical and radiological outcomes

Introduction

The current methods for measuring femoral torsion have limitations, including variability and inaccuracies. Existing 3D methods are not reliable for abnormal femoral anteversion measurement. A new 3D method is needed for accurate measurement and planning of proximal femoral osteotomies. Currently available software for viewing and modelling CT data lacks measurement capabilities. The MSK Hip planner aims to address these limitations by combining measurement, planning, and analysis functionalities into one tool. We aim to answer 5 key questions: Is there a difference between 2D measurement methods? Is there a difference between 3D measurement methods? Is there a difference between 2D and 3D measurement methods? Are any of the measurement methods affected by the presence of osteoarthritis or a CAM deformity?

Purpose:. Anterior positioning of a cephomedullary nail (CMN) in the distal femur occurs in up to 88% of cases. Conventionally, this is considered to occur because of a mismatch between the radius of curvature (ROC) of the femur and that of available implants. The hypothesis for this study was that the relative thicknesses of the cortices of the femur, particularly the posterior cortex are important in determining the final position of an intramedullary implant and that the posterior cortical thickness corresponds to the linea aspera anatomically. The aim was to determine if these measurements changed with age. Method:. This study used the data from CT scans undertaken as part of routine clinical practice in 919 patients with intact left femora (median age 66 years, range 20–93 years; 484 male and 435 female). The linea aspera was defined manually on the template bone by consensus between two orthopaedic surgeons and two anatomists. The length of the femur was measured from the tip of the greater trochanter proximally to the intercondylar notch distally. Transverse intervals were plotted on the femur between 25%–60% femoral bone length (5% increments). The linea aspera was then defined at each interval on the template bone and mapped automatically to all individual femora in the database. Results:. The linea aspera was found to be internally rotated as compared to the sagittal plane referenced off the posterior femoral condyles. An age related change in the posterior/anterior cortical thickness ratio was demonstrated. This ratio increases in all age groups from 25–60% bone length being maximal around 45–55% bone length. The ≥80 year old cohort shows a disproportional posterior/anterior ratio increase of 70.0% from 25–50% bone length as compared to 48.1% for the <40 year old cohort which is statistically significant (Mann-Whitney-Test p<0.05, α = 5%). Conclusion:. This study presents a novel method of investigating femoral anatomy with directly relevance to orthopaedic procedures. This study has shown that assessment in the sagittal plane may be inaccurate because the linea aspera changes in this plane throughout the length of the femur. It also shows the loss of the centering influence of the corticies with age with a relative thinning of the anterior cortex with a concomitant thickening of the posterior cortex moving distally in the femur. This has a very direct and significant influence on the positioning of intramedullary femoral implants explaining the preponderance of anterior malpositioning of intramedullary implants in the elderly

Introduction

The value of collared stems for uncemented implants remains controversial. Some comparative studies have demonstrated advantages of collared stems regarding the potential for subsidence. Other studies with longer follow-up have shown no adverse effect of the use of a collar regarding the femoral component survivorship. To date, the adequate size of the collar with regards to the anatomy of the proximal femur has never been studied.

The goal of this study was to assess whether the size of the collar needs to be adjusted according to the size of the femoral component used, and according to the use of a standard or a lateralized component.

Femoral component sizing can play a critical role in the clinical outcome and success of a TKR prosthesis. In particular, achieving the correct AP dimension for the femur is important to ensure correct balancing and to maintain flexion/extension spacing and the ML width dictates bone coverage which, if insufficient, can cause complications or affect long-term outcomes.

There has been some discussion in the literature about the optimal femoral component shape and size with reports of differences in anatomy between male and female patients or those of larger or smaller stature. The majority of these publications have been conducted on normal anatomy with un-cut bone, reporting on the epicondylar width of the femur which is difficult to relate back to the dimensions of a prosthesis. Some studies have measured resected bone, however, the prosthesis and instruments used to make the cuts dictate the amount of bone removed anteriorly and posteriorly which, in turn affect the footprint of exposed bone that is measured.

Data was gathered to assess whether a generic prosthesis with a standard AP/ML sizing ratio could be used to cover the range of femoral sizes dictated by a Caucasian population of 26 male and 26 female patients. MRI scans were obtained for these patients, all between 20 and 45 years of age and diagnosed with a meniscal tear. A theoretical size range for a prosthesis was determined from an analysis of literature data and a review of currently available devices. This consisted of 8 femoral sizes ranging from 50 – 74.5 mm in AP dimension with a constant AP/ML ratio of 0.9. Each MRI scan was viewed in the sagital plane and the maximum AP dimension was measured. This was sized to the closest available femoral component using the criteria of matching the existing articulating geometry as closely as possible. A ‘virtual’ distal condyle cut was made on the scan relating to the component size and the ML dimension of the resected bone was taken. The measured ML data was then compared to the implant dimension for each subject and component overhang/underhang was determined.

An appropriate femoral component match was found in all cases with a mean AP dimensional undersize of 1.71 mm across all patients (range: 0.16 – 3.77 mm). The mean ML femoral component overhang was 0.34 mm for the male population, 1.52 mm for the female population and 0.89 mm for all 52 patients. These values were all considered to be well within an acceptable range and not be significant in terms of clinical outcome. No patient was too large for the largest component, however no patient in the population that was assessed matched the smallest of the 8 components.

This simple dimensional assessment has shown that using a prosthesis with a standard AP/ML ratio, it is possible to accommodate a mixed gender population. The data reported here suggests that the anatomical differences between men and women femora is not hugely significant and can be covered with a common implant provided a sufficient size range is used.

Finsbury Orthopaedics would like to acknowledge Dr. Pinskerova for providing the MRI scans.

The aim of this retrospective cohort study was to identify any difference in femoral offset as measured on pre-operative anteroposterior (AP) radiographs of the pelvis, AP radiographs of the hip and corresponding CT scans in a consecutive series of 100 patients with primary end-stage osteoarthritis of the hip (43 men and 57 women with a mean age of 61 years (45 to 74) and a mean body mass index of 28 kg/m² (20 to 45)).

Patients were positioned according to a standardised protocol to achieve reproducible projection and all images were calibrated. Inter- and intra-observer reliability was evaluated and agreement between methods was assessed using Bland-Altman plots.

In the entire cohort, the mean femoral offset was 39.0 mm (95% confidence interval (CI) 37.4 to 40.6) on radiographs of the pelvis, 44.0 mm (95% CI 42.4 to 45.6) on radiographs of the hip and 44.7 mm (95% CI 43.5 to 45.9) on CT scans. AP radiographs of the pelvis underestimated femoral offset by 13% when compared with CT (p < 0.001). No difference in mean femoral offset was seen between AP radiographs of the hip and CT (p = 0.191).

Our results suggest that femoral offset is significantly underestimated on AP radiographs of the pelvis but can be reliably and accurately assessed on AP radiographs of the hip in patients with primary end-stage hip osteoarthritis.

We, therefore, recommend that additional AP radiographs of the hip are obtained routinely for the pre-operative assessment of femoral offset when templating before total hip replacement.

Purpose

Tibial and femoral component overhang in total knee arthroplasty (TKA) is a source of pain, thus is it important to understand anatomic differences between races to minimize overhang by matching the tibial and femoral shaft axis to the knee articular surface. Thus, this study compared knee morphology between Caucasian and East Asian individuals to determine the optimal placement of tibial and femoral stems.

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

Aims. The aim of this retrospective study was to assess the incidence of early periprosthetic femoral fracture (PFF) associated with Charnley-Kerboull (CK) femoral components cemented according to the ‘French paradox’ principles through the Hueter anterior approach (HAA) in patients older than 70 years. Methods. From a prospectively collected database, all short CK femoral components implanted consecutively from January 2018 to May 2022 through the HAA in patients older than 70 years were included. Exclusion criteria were age below 70 years, use of cementless femoral component, and approaches other than the HAA. A total of 416 short CK prostheses used by 25 surgeons with various levels of experience were included. All patients had a minimum of one-year follow-up, with a mean of 2.6 years (SD 1.1). The mean age was 77.4 years (70 to 95) and the mean BMI was 25.3 kg/m. 2. (18.4 to 43). Femoral anatomy was classified according to Dorr. The measured parameters included canal flare index, morphological cortical index, canal-calcar ratio, ilium-ischial ratio, and anterior superior iliac spine to greater trochanter (GT) distance. Results. Among the 416 THAs, two PFFs (0.48% (95% confidence interval 0.13 to 1.74)) were observed, including one Vancouver type B2 fracture 24 days postoperatively and one intraoperative Vancouver type B1 fracture. Valgus malalignment and higher canal bone ratio were found to be associated with PFF. Conclusion. This study demonstrated that short CK femoral components cemented according to the French paradox were associated with a low rate of early PFF (0.48%) in patients aged over 70 years. Longer follow-up is warranted to further evaluate the rate of fracture that may occur during the bone remodelling process and with time. Cite this article: Bone Joint J 2024;106-B(3 Supple A):67–73

Intraoperative fractures although rare are one of the complications known to occur while performing a total hip arthroplasty (THA). However, due to lower incidence rates there is currently a gap in this area of literature that systematically reviews this important issue of complications associated with THA. Method: We looked into Electronic databases including PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), the archives of meetings of orthopaedic associations and the bibliographies of included articles and asked experts to identify prospective studies, published in any language that evaluated intra-operative fractures occurring during total hip arthroplasty from the year 1950-2020. The screening, data extraction and quality assessment were carried out by two researchers and if there was any discrepancy, a third reviewer was involved. Fourteen studies were identified. The reported range of occurrence of fracture while performing hip replacement surgery was found to be 0.4-7.6%. Major risk factors identified were surgical approaches, Elderly age, less Metaphyseal-Diaphyseal Index score, change in resistance while insertion of the femur implants, inexperienced surgeons, uncemented femoral components, use of monoblock elliptical components, implantation of the acetabular components, patients with ankylosing spondylitis, female gender, uncemented stems in patients with abnormal proximal femoral anatomy and with cortices, different stem designs, heterogeneous fracture patterns and toothed design. Intraoperative fractures during THA were managed with cerclage wire, femoral revision, intramedullary nail and cerclage wires, use of internal fixation plates and screws for management of intra operative femur and acetabular fractures. The main reason for intraoperative fracture was found to be usage of cementless implants but planning and timely recognition of risk factors and evaluating them is important in management of intraoperative fractures. Adequate surgical site exposure is critical especially during dislocation of hip, reaming of acetabulum, impaction of implant and preparing the femoral canal for stem insertion. Eccentric and increased reaming of acetabulum to accommodate a larger cup is to be avoided, especially in females and elderly patients as the acetabulum is thinner. However, this area requires more research in order to obtain more evidence on effectiveness, safety and management of intraoperative fractures during THA

Primary total hip replacement (THR) in patients with abnormal/altered proximal femoral anatomy/narrow canals presents a technical challenge. There are only limited standard prosthetic stems available to deal with narrow canals or abnormal morphology. Many prefer to use expensive custom implants which often have a lag time to manufacture and do not always have long term published outcomes. We present results of the Asian C-stem (which is a standard implant available on the shelf) used in patients predominantly of Caucasian origin with abnormal proximal femoral anatomy. We retrospectively reviewed clinic-radiological results of 131 patients (131 stems) who underwent primary THR using Asian C-stem at Wrightington Hospital till their latest follow up. Revision for any reason was considered as primary end point. Mean age at surgery was 50.8 years (16 – 80). The 2 commonest indications were primary osteoarthritis (66 patients) and hip dysplasia (54 patients). Mean follow up was 43.5 months with a minimum follow up of 12 months and maximum follow up of 97 months. There were 2 recurrent dislocations and 1 hip subluxed twice. One dislocation needed revision surgery. 1 patient underwent acetabular revision for loosening. There was no stem failure, obvious loosening or loss of fixation in any patients in our series with regards to the Asian C-stem. There were no infections and intra-operative perforations or fractures. C-stem Asian is a reliable implant for patients undergoing THR with abnormal proximal femoral anatomy or narrow canals. Long term follow up is essential

Cementless femoral components have an excellent track record that includes efficient implantation and long-term survival, thus are the predominant stem utilised in North America. Femoral component stability and resistance to subsidence are critical for osseointegration and clinical success. Implant design, surgical technique, anatomic fit, and patient characteristics, such as bone quality, can all effect initial implant stability and resistance to subsidence. Variability in stem shape and in the anatomy of the proximal femoral metaphysis has been implicated in the failure of some stem designs. Biologic fixation obtained with osseointegration of cementless implants may improve implant longevity in young, active, and obese patients. Lack of intimate fit can lead to clinical complications such as subsidence, aseptic loosening, and peri-prosthetic fracture. Currently, there are several stem designs, all of which aim to achieve maximal femoral stability and minimal subsidence and include: Fit and Fill / Double Taper Proximally Porous Coated Stems; Parallel Sided Taper Wedge or “Blade” Stems; Wagner Style Conical Shape Splined Titanium Stems; Tapered Rectangular Cross-Section Zweymuller Stem; Fully-Porous Coated Stems; Modular Proximal Sleeve Fluted Stem; Anatomic Proximally Porous Coated Stems. The majority of patients with relatively straightforward anatomy can be treated with any of the aforementioned femoral implant types. However, more complicated femoral anatomy frequently requires a particular implant type to maximise stability and promote osseointegration. Stems with femoral deformity in the meta-diaphyseal region may require a shorter stem in order to avoid an osteotomy. Distorted femoral anatomy typically seen in childhood diseases, such as dysplasia, may require a modular proximal sleeve tapered fluted stem or Wagner style cone stem to impart optimal stem anteversion separate from the native femoral neck version. The most severe forms of dysplasia may require a shortening osteotomy and subsequent distal fixation and neck version flexibility, which can be addressed with a modular proximal sleeve fluted or fully porous coated stem. A stovepipe or osteoporotic femur may require a stem that engages more distally such as a conical splined tapered stem, a fully porous coated stem or even a cemented stem to achieve adequate stability. Finally, obese patients are a particular challenge and emerging data suggests that a morphologically based parallel-sided taper wedge stems may confer greater stability and resistance to subsidence in these patients. Ultimately, an appropriate selection algorithm will facilitate an appropriate match of the patient morphology with femoral implant geometry that facilitates stable fixation and osseointegration

Aims

The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases.

Introduction and Aims: Legg-Calve-Perthes disease and slipped capital femoral epiphysis are hip disorders that may result in the alteration of proximal femoral anatomy and subsequent osteoarthritis. LCP often results in a flattened head and short femoral neck; SCFE residual deformity is a retroverted head upon a wide femoral neck. Because of the low head to neck ratio and short neck length in these patients, surface arthroplasty is especially technically difficult. Method: We examined a cohort of patients with either LCP or SCFE who underwent surface replacement of the hip to assess clinical results and identify pre-operative radiographic factors unique to this group. All patients with arthritis of the hip secondary to either LCP or SCFE, who underwent surface replacement between 1996–2002, were included. Proximal femoral anatomy was assessed by measuring the neck and head length, flattening of the head, anterior head offset and lateral head offset. Hip ROM was measured and SF-12 and UCLA Hip scores were calculated. Results: Fourteen patients with LCP and 11 patients with SCFE had undergone surface replacement with an average age of 38 years; the mean time to follow-up was 26.2 months. Pre-operative radiographs revealed a head-neck ratio of 1.3 in the LCP group and 1.2 in the SCFE group. The amount of head offset was 9.4mm anterior and 6.4mm lateral in the LCP group; and 8.8mm and 4.4mm in the SCFE group. Neck and head length was 42mm in the LCP patients and 56.5mm in the SCFE patients; this measured 46 and 53mm post-operatively. No revisions had been performed in either group. The UCLA scores, SF-12 scores, and hip ROM did not differ from a cohort of patients who had undergone resurfacing for other reasons. No femoral neck fractures occurred in either group. Conclusion: Despite technically difficult surgeries for hip resurfacing in these patients because of a flattened head and short neck in LCP, and wide femoral neck with retroverted heads in SCFE, the results to date have been good. By taking extra care to avoid notching the neck on the anterior and lateral tension sides, satisfactory results can be achieved

Anterior cruciate ligament (ACL) injuries are among the most common and debilitating knee injuries in professional athletes with an incidence in females up to eight-times higher than their male counterparts. ACL injuries can be career-threatening and are associated with increased risk of developing knee osteoarthritis in future life. The increased risk of ACL injury in females has been attributed to various anatomical, developmental, neuromuscular, and hormonal factors. Anatomical and hormonal factors have been identified and investigated as significant contributors including osseous anatomy, ligament laxity, and hamstring muscular recruitment. Postural stability and impact absorption are associated with the stabilizing effort and stress on the ACL during sport activity, increasing the risk of noncontact pivot injury. Female patients have smaller diameter hamstring autografts than males, which may predispose to increased risk of re-rupture following ACL reconstruction and to an increased risk of chondral and meniscal injuries. The addition of an extra-articular tenodesis can reduce the risk of failure; therefore, it should routinely be considered in young elite athletes. Prevention programs target key aspects of training including plyometrics, strengthening, balance, endurance and stability, and neuromuscular training, reducing the risk of ACL injuries in female athletes by up to 90%. Sex disparities in access to training facilities may also play an important role in the risk of ACL injuries between males and females. Similarly, football boots, pitches quality, and football size and weight should be considered and tailored around females’ characteristics. Finally, high levels of personal and sport-related stress have been shown to increase the risk of ACL injury which may be related to alterations in attention and coordination, together with increased muscular tension, and compromise the return to sport after ACL injury. Further investigations are still necessary to better understand and address the risk factors involved in ACL injuries in female athletes.

Cite this article: Bone Jt Open 2024;5(2):94–100.

Aims

The Birmingham Hip Resurfacing (BHR) arthroplasty has been used as a surgical treatment of coxarthrosis since 1997. We present 20-year results of 234 consecutive BHRs performed in our unit.

Aims

Femoral component anteversion is an important factor in the success of total hip arthroplasty (THA). This retrospective study aimed to investigate the accuracy of femoral component anteversion with the Mako THA system and software using the Exeter cemented femoral component, compared to the Accolade II cementless femoral component.

Aims

The risk of mechanical failure of modular revision hip stems is frequently mentioned in the literature, but little is currently known about the actual clinical failure rates of this type of prosthesis. The current retrospective long-term analysis examines the distal and modular failure patterns of the Prevision hip stem from 18 years of clinical use. A design improvement of the modular taper was introduced in 2008, and the data could also be used to compare the original and the current design of the modular connection.

Aims

The Exeter V40 femoral stem is the most implanted stem in the National Joint Registry (NJR) for primary total hip arthroplasty (THA). In 2004, the 44/00/125 stem was released for use in ‘cement-in-cement’ revision cases. It has, however, been used ‘off-label’ as a primary stem when patient anatomy requires a smaller stem with a 44 mm offset. We aimed to investigate survival of this implant in comparison to others in the range when used in primary THAs recorded in the NJR.