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Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_6 | Pages 14 - 14
1 Feb 2013
Lee P Neelapala V O'Hara J
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Introduction. Perthes' disease is associated with coxa breva, plana and magna, and a high riding prominent greater trochanter causing abductor shortening and weakness, leg shortening and extra-articular impingement. A trochanteric advancement with an infero-lateralising oblique sliding osteotomy of the proximal femur would lengthen femoral neck, improve abductor length and strength, relieve impingement and improve leg length. We assessed the mid-term outcomes for this procedure. Method. We included patients who underwent the operation by the senior author (JNOH) with more than 2 years follow-up. The osteotomies were performed minimally invasively under image intensifier guidance and fixed with blade plate or locking plates. We assessed functional scores, radiological changes in neck length, Tonnis grading for arthritis and evidence of femoral head avascular necrosis, time interval for conversion to hip arthroplasty and associated complications. Results. Twenty four patients (25 hips) underwent the procedure at mean age of 18.7 years (range:9.3–38.8) with a mean follow-up of 5 years (range:2–13.8). At the last assessment, the mean Oxford Hip Score was 41.6 (range:58–27), Non-Arthritic Hip Score was 53.4 (range:25–77) and UCLA activity score was 4.2 (range:2–6). For changes in neck length, the mean “Head-centre-to-Greater-trochanteric-tip-distance” was 60 mm (range:43–78) compared to 39 mm (range:30–48) pre-operatively and the mean “Head-centre-to-Lesser-trochanteric-tip-distance” was 54 mm (range:47–64) compared to 37 mm (range:31–41) pre-operatively. The mean Tonnis grade was 1.5 (range:1–3) compared to 1.3 (range:1–2) pre-operatively. Two patients underwent arthroplasty conversion at 2 and 13.8 years later. One patient needed head-neck debridement for impingement and 2 patients underwent trochanteric refixation for non-union. There were no cases of avascular necrosis. Discussion. Symptomatic Perthes' hip deformity in adolescents and young adults is difficult to treat with joint preserving surgery. The mid-term clinical, functional and radiological results for double proximal femur osteotomy are encouraging


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 103 - 103
1 Jan 2013
Lee P Neelapala V O'Hara J
Full Access

Introduction. Perthes disease is associated with coxa breva, plana and magna, and a high riding prominent greater trochanter causing abductor shortening and weakness, leg shortening and extra-articular impingement. A trochanteric advancement with an infero-lateralizing sliding osteotomy of the proximal femur would lengthen femoral neck, improve abductor length and strength, relieve impingement and improve leg length. We assessed the mid-term outcomes for this procedure. Method. We included patients who underwent the operation by the senior author (JNOH) with more than 2 years follow-up. The osteotomies were performed under image intensifier guidance and fixed with blade plate or locking plates. We assessed functional scores, radiological changes in neck length, Tonnis grading for arthritis and evidence of progression in femoral head avascular necrosis, time interval for conversion to hip arthroplasty and associated complications. Results. Twenty four patients (25 hips) underwent the procedure at mean age of 18.7 years (range:9.3–38.8) with a mean follow-up of 5 years (range:2–13.8). At the last assessment, the mean Oxford Hip Score was 41.6 (range:58–27), Non-Arthritic Hip Score was 53.4 (range:25–77) and UCLA activity score was 4.2 (range:2–6). For changes in neck length, the mean “Head-centre-to-Greater-trochanteric-tip-distance” was 60 mm (range:43–78) compared to 39 mm (range:30–48) pre-operatively and the mean “Head-center-to-Lesser-trochanteric-tip-distance” was 54 mm (range:47–64) compared to 37 mm (range:31–41) pre-operatively. The mean Tonnis grade was 1.5 (range:1–3) compared to 1.3 (range:1–2) pre-operatively. Two patients underwent arthroplasty conversion at 2 and 13.8 years later. One patient needed head-neck debridement for impingement and 2 patients underwent trochanteric refixation for non-union. There was no progression in avascular necrosis of femoral head. Discussion. Symptomatic Perthes hip deformity in adolescents and young adults is difficult to treat with joint preserving surgery. The mid-term clinical, functional and radiological results for double proximal femur osteotomy are encouraging


Bone & Joint Research
Vol. 3, Issue 4 | Pages 130 - 138
1 Apr 2014
Shapiro F Connolly S Zurakowski D Flynn E Jaramillo D

Objectives

An experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia.

Methods

Intracapsular circumferential ligation at the base of the femoral neck and sectioning of the ligamentum teres were performed in three week old piglets. MRI was then used for qualitative and quantitative studies of the acetabula in operated and non-operated hips in eight piglets from 48 hours to eight weeks post-surgery. Specimen photographs and histological sections of the acetabula were done at the end of the study.


The Journal of Bone & Joint Surgery British Volume
Vol. 75-B, Issue 5 | Pages 760 - 763
1 Sep 1993
Broughton N Menelaus M Cole W Shurtleff D

We studied 1061 children with myelomeningocele, reviewing 3184 pelvic radiographs from 802 patients. Hip dislocation had occurred by the age of 11 years in 28% of children with a thoracic neurosegmental level, 30% of those with an L1/2 level, 36% of L3, 22% of L4, 7% of L5 and only 1% of those with sacral levels. Hip dislocation was not inevitable even when there was maximal muscle imbalance about the hip. The average hip flexion contracture in children aged 9 to 11 years was significantly greater in those with thoracic (22 degrees) and L1/2 (33 degrees) levels than in those with L4 (9 degrees), L5 (5 degrees) or sacral (4 degrees) levels. Our findings indicate that muscle imbalance is not a significant factor in the production of flexion deformity or dislocation of the hip; both are commonly seen in the absence of imbalance. The restoration of muscle balance should no longer be considered to be the principal aim of the management of the hip in children with myelomeningocele.


Orthopaedic Proceedings
Vol. 91-B, Issue SUPP_I | Pages 64 - 64
1 Mar 2009
Moroni A Romagnoli M Cadossi M Pegreffi F Giannini S
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INTRODUCTION Metal-on-metal hip resurfacing (MOMHR) has recently been reintroduced as a viable treatment option for young active patients. A short femoral neck and insufficient head are common deformities following CDH, Perthes disease and SFCE. Therefore, severity of these deformities is a contraindication for MOMHR, as contact between the femoral resurfacing component and the femoral head would be inadequate and off-set insufficient.

METHODS 32 patients with severe deformity of the hip were treated with Birmingham hip resurfacing and head lengthening. We used a standard acetabular component in 18 patients and a CDH acetabular component and supplementary screw fixation in 14. Bone chips produced while reaming the acetabulum were impacted on the femoral head to achieve the desired length, as evaluated on pre-op x-rays. Rehabilitation included no weight-bearing for 1 month and partial weight-bearing for another month.

RESULTS Median patient age was 44 years. Median head lengthening was 1.2 cm. Minimum follow-up was 3.1 years, maximum 5.2. Mean Harris Hip Score was 98. At follow-up 82% of the patients were involved in heavy or moderately heavy work. 34% of the patients practiced sports. Co and Cr serum concentrations at 25 months were respectively ng/ml 1.76, and 0.75. DXA analysis of the proximal femur showed complete recovery of BMD in Gruen zone 1 and increased in zone 7 (p= 0.05). There were no major complications.

DISCUSSION AND CONCLUSIONS The absence of major complications and the quality of our results support this technique in young active patients with severe deformity of the hip.


Orthopaedic Proceedings
Vol. 106-B, Issue SUPP_16 | Pages 37 - 37
19 Aug 2024
Rego P Mafra I Viegas R Silva C Ganz R
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Executing an extended retinacular flap containing the blood supply for the femoral head, reduction osteotomy (FHO) can be performed, increasing the potential of correction of complex hip morphologies. The aim of this study was to analyse the safety of the procedure and report the clinical and radiographic results in skeletally mature patients with a minimum follow up of two years. Twelve symptomatic patients (12 hips) with a mean age of 17 years underwent FHO using surgical hip dislocation and an extended soft tissue flap. Radiographs and magnetic resonance imaging producing radial cuts (MRI) were obtained before surgery and radiographs after surgery to evaluate articular congruency, cartilage damage and morphologic parameters. Clinical functional evaluation was done using the Non-Arthritic Hip Score (NAHS), the Hip Outcome Score (HOS), and the modified Harris Hip Score (mHHS). After surgery, at the latest follow-up no symptomatic avascular necrosis was observed and all osteotomies healed without complications. Femoral head size index improved from 120 ± 10% to 100 ± 10% (p<0,05). Femoral head sphericity index improved from 71 ± 10% before surgery to 91 ± 7% after surgery (p<0,05). Femoral head extrusion index improved from 37 ± 17% to 5 ± 6% (p< 0,05). Twenty five percent of patients had an intact Shenton line before surgery. After surgery this percentage was 75% (p<0,05). The NAHS score improved from a mean of 41 ± 18 to 69 ± 9 points after surgery (p< 0,05). The HOS score improve from 56 ± 24 to 83 ± 17 points after surgery (p< 0,05) and the mHHS score improved from 46 ± 15 before surgery to 76 ± 13 points after surgery (p< 0,05). In this series, femoral head osteotomy could be considered as safe procedure with considerable potential to correct hip deformities and improve patients reported outcome measures (PROMS). Level of evidence - Level IV, therapeutic study. Keywords - Femoral head osteotomy, Perthes disease, acetabular dysplasia, coxa plana


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 40 - 46
1 May 2024
Massè A Giachino M Audisio A Donis A Giai Via R Secco DC Limone B Turchetto L Aprato A

Aims

Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes’ disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach.

Methods

From September 2015 to December 2021, 13 FHROs were performed on 11 patients for Perthes’ disease in two centres. Of these, 11 hips had an associated PAO. A specific CT- and MRI-based protocol for virtual simulation of the corrections was developed. Outcomes were assessed with radiological parameters (sphericity index, extrusion index, integrity of the Shenton’s line, lateral centre-edge angle (LCEA), Tönnis angle), and clinical parameters (range of motion, visual analogue scale (VAS) for pain, Merle d'Aubigné-Postel score, modified Harris Hip Score (mHHS), and EuroQol five-dimension five-level health questionnaire (EQ-5D-5L)). Early and late complications were reported.


The Bone & Joint Journal
Vol. 100-B, Issue 12 | Pages 1551 - 1558
1 Dec 2018
Clohisy JC Pascual-Garrido C Duncan S Pashos G Schoenecker PL

Aims. The aims of this study were to review the surgical technique for a combined femoral head reduction osteotomy (FHRO) and periacetabular osteotomy (PAO), and to report the short-term clinical and radiological results of a combined FHRO/PAO for the treatment of selected severe femoral head deformities. Patients and Methods. Between 2011 and 2016, six female patients were treated with a combined FHRO and PAO. The mean patient age was 13.6 years (12.6 to 15.7). Clinical data, including patient demographics and patient-reported outcome scores, were collected prospectively. Radiologicalally, hip morphology was assessed evaluating the Tönnis angle, the lateral centre to edge angle, the medial offset distance, the extrusion index, and the alpha angle. Results. The mean follow-up was 3.3 years (2 to 4.6). The modified Harris Hip Score improved by 33.0 points from 53.5 preoperatively to 83.4 postoperatively (p = 0.03). The Western Ontario McMasters University Osteoarthritic Index score improved by 30 points from 62 preoperatively to 90 postoperatively (p = 0.029). All radiological parameters showed significant improvement. There were no long-term disabilities and none of the hips required early conversion to total hip arthroplasty. Conclusion. FHRO combined with a PAO resulted in clinical and radiological improvement at short-term follow-up, suggesting it may serve as an appropriate salvage treatment option for selected young patients with severe symptomatic hip deformities


Bone & Joint Research
Vol. 12, Issue 1 | Pages 22 - 32
11 Jan 2023
Boschung A Faulhaber S Kiapour A Kim Y Novais EN Steppacher SD Tannast M Lerch TD

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.

Methods

A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method).


The Bone & Joint Journal
Vol. 105-B, Issue 6 | Pages 711 - 716
1 Jun 2023
Ali MS Khattak M Metcalfe D Perry DC

Aims

This study aimed to evaluate the relationship between hip shape and mid-term function in Perthes’ disease. It also explored whether the modified three-group Stulberg classification can offer similar prognostic information to the five-group system.

Methods

A total of 136 individuals aged 12 years or older who had Perthes’ disease in childhood completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility score (function), Nonarthritic Hip Score (NAHS) (function), EuroQol five-dimension five-level questionnaire (EQ-5D-5L) score (quality of life), and the numeric rating scale for pain (NRS). The Stulberg class of the participants’ hip radiographs were evaluated by three fellowship-trained paediatric orthopaedic surgeons. Hip shape and Stulberg class were compared to PROM scores.


Bone & Joint 360
Vol. 13, Issue 3 | Pages 42 - 45
3 Jun 2024

The June 2024 Children’s orthopaedics Roundup360 looks at: Proximal femoral unicameral bone cysts: is ESIN the answer?; Hybrid-mesh casts in the conservative management of paediatric supracondylar humeral fractures: a randomized controlled trial; Rate and risk factors for contralateral slippage in adolescents treated for slipped capital femoral epiphysis; CRP predicts the need to escalate care after initial debridement for musculoskeletal infection; Genu valgum in paediatric patients presenting with patellofemoral instability; Nusinersen therapy changed the natural course of spinal muscular atrophy type 1: what about spine and hip?; The necessity of ulnar nerve exploration and translocation in open reduction of medial humeral epicondyle fractures in children.


Bone & Joint 360
Vol. 12, Issue 4 | Pages 38 - 41
1 Aug 2023

The August 2023 Children’s orthopaedics Roundup360 looks at: DDH: What can patients expect after open reduction?; Femoral head deformity associated with hip displacement in non-ambulatory cerebral palsy; Bony hip reconstruction for displaced hips in patients with cerebral palsy: is postoperative immobilization indicated?; Opioid re-prescriptions after ACL reconstruction in adolescents are associated with subsequent opioid use disorder; Normative femoral and tibial lengths in a modern population of USA children; Retrospective analysis of associated anomalies in 636 patients with operatively treated congenital scoliosis; Radiological hip shape and patient-reported outcome measures in healed Perthes’ disease; Significantly displaced adolescent posterior sternoclavicular joint injuries.


Bone & Joint Open
Vol. 4, Issue 8 | Pages 635 - 642
23 Aug 2023
Poacher AT Hathaway I Crook DL Froud JLJ Scourfield L James C Horner M Carpenter EC

Aims

Developmental dysplasia of the hip (DDH) can be managed effectively with non-surgical interventions when diagnosed early. However, the likelihood of surgical intervention increases with a late presentation. Therefore, an effective screening programme is essential to prevent late diagnosis and reduce surgical morbidity in the population.

Methods

We conducted a systematic review and meta-analysis of the epidemiological literature from the last 25 years in the UK. Articles were selected from databases searches using MEDLINE, EMBASE, OVID, and Cochrane; 13 papers met the inclusion criteria.


The Bone & Joint Journal
Vol. 105-B, Issue 7 | Pages 760 - 767
1 Jul 2023
Tanaka S Fujii M Kawano S Ueno M Sonohata M Kitajima M Mawatari D Mawatari M

Aims

The aims of this study were to validate the Forgotten Joint Score-12 (FJS-12) in the postoperative evaluation of periacetabular osteotomy (PAO), identify factors associated with joint awareness after PAO, and determine the FJS-12 threshold for patient-acceptable symptom state (PASS).

Methods

Data from 686 patients (882 hips) with hip dysplasia who underwent transposition osteotomy of the acetabulum, a type of PAO, between 1998 and 2019 were reviewed. After screening the study included 442 patients (582 hips; response rate, 78%). Patients who completed a study questionnaire consisting of the visual analogue scale (VAS) for pain and satisfaction, FJS-12, and Hip disability and Osteoarthritis Outcome Score (HOOS) were included. The ceiling effects, internal consistency, convergent validity, and PASS thresholds of FJS-12 were investigated.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 32 - 39
1 May 2024
Briem T Stephan A Stadelmann VA Fischer MA Pfirrmann CWA Rüdiger HA Leunig M

Aims

The purpose of this study was to evaluate the mid-term outcomes of autologous matrix-induced chondrogenesis (AMIC) for the treatment of larger cartilage lesions and deformity correction in hips suffering from symptomatic femoroacetabular impingement (FAI).

Methods

This single-centre study focused on a cohort of 24 patients with cam- or pincer-type FAI, full-thickness femoral or acetabular chondral lesions, or osteochondral lesions ≥ 2 cm2, who underwent surgical hip dislocation for FAI correction in combination with AMIC between March 2009 and February 2016. Baseline data were retrospectively obtained from patient files. Mid-term outcomes were prospectively collected at a follow-up in 2020: cartilage repair tissue quality was evaluated by MRI using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported outcome measures (PROMs) included the Oxford Hip Score (OHS) and Core Outcome Measure Index (COMI). Clinical examination included range of motion, impingement tests, and pain.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 336 - 336
1 Mar 2013
Song I Lee C
Full Access

Background. We have performed total knee arthroplasties for valgus and varus in the knees of one person and investigate the clinical characteristics of these patients and the relationship between the kind of deformity and postoperative result. Methods. From March 2002 to February 2010, 25 patients who had simultaneous varus and valgus knee deformities underwent total knee arthroplasties and followed more than 12 months were included. The average age was 66.9 years and the average follow-up period was 61.1 months. Follow-up imaging assessments were taken and clinical outcome were evaluated using HSS score at last follow-up. Results. 11 cases had more pain in varus knee and 8 cases had more pain in valgus knee preoperatively. In 11 cases, degenerative scoliosis were associated with the knee deformity and among the cases, 10 cases had valgus deformities in concave side of scoliosis. In three cases, hip deformities were noted in ipsilateral side of the valgus deformity. One case showed both hip deformities with ankylosing spondylitis. Preoperative mean valgus angle was 11.4 degree and varus angle was 7.5 degree. Postoperative valgus and varus angle improved to 6.3 and −5.7 degree. HSS score improved from 64.3 to 84.7 point in valgus deformities and from 62.1 to 85.1 point in varus deformities. Postoperative patellar clunk syndrome was identified in one valgus knee, but resolved by arthroscopic debridement. And postoperatively, one case showed out-toeing gait caused by equinovarus deformity in varus knee, but resolved by correction of foot deformity. Conclusions. Simultaneous or staged total knee arthroplasties in patients with simultaneous varus with contralateral valgus knee deformities brought satisfactory outcomes with regard to objective orthopedic criteria such as radiographic and clinical results. Concave aspect of scoliosis and hip deformity correlate with valgus knee in statistically. But rheumatoid factor and VDRL do not correlate with valgus deformity. And we found no significant difference between the kind of deformity and postoperative result


Bone & Joint Open
Vol. 3, Issue 10 | Pages 759 - 766
5 Oct 2022
Schmaranzer F Meier MK Lerch TD Hecker A Steppacher SD Novais EN Kiapour AM

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.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_10 | Pages 71 - 71
1 May 2016
Tamaki T Miura Y Oinuma K Higashi H Kaneyama R Shiratsuchi H
Full Access

Background. Pre-operative autologous blood donation is recommended as a means of reducing the need for allogeneic transfusion before simultaneous bilateral total hip arthroplasty (THA). However, there have been few reports on the optimal amount of autologous donation for this procedure. In this study we sought to determine the amount of autologous blood required for patient undergoing simultaneous bilateral THA using the direct anterior approach. Methods. We retrospectively enrolled 325 consecutive patients (650 hips) underwent simultaneous bilateral primary THA from January 2012 to June 2014. Thirty-three patients were men and 290 patients were women. The patients’ mean age at THA was 59.1 years. All THAs were performed using the direct anterior approach. Intraoperative blood salvage was applied for all patients and postoperative blood salvage was not applied for any patients. Results. The mean intraoperative blood loss and the mean operative time for the bilateral procedure were 413±165 g and 87.2±12.3 minutes, respectively. Two hundreds and forty-one of the 325 patients (74.2%) donated an average of 1.9 (range, 1–2) units of autologous blood before the operation. The mean hemoglobin levels on the preoperative day, postoperative day 1 and postoperative day 5 were 12.5g/dl, 10.5 g/dl and 9.5 g/dl, respectively. Only 1 patient (0.3%) required postoperative transfusions of allogeneic blood. All of the autologous units collected were transfused, and no units were wasted. Conclusion. Simultaneous bilateral THA can be performed without allogenic blood transfusion in 99.7% of patients. We could not find out significant effectiveness of an average of 1.9 units of autologous blood donation for this procedure in this study. We concluded that simultaneous bilateral THA can be performed without autologous blood donation in healthy patients without severe hip deformity. Whereas, preoperative donation of autologous blood might be suitable for patients with low body weight or patients with severe hip deformity. The minimally invasive aspect of the direct anterior approach seems to allow a low rate of allogeneic blood transfusion in the study


The Bone & Joint Journal
Vol. 106-B, Issue 8 | Pages 775 - 782
1 Aug 2024
Wagner M Schaller L Endstrasser F Vavron P Braito M Schmaranzer E Schmaranzer F Brunner A

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.

Methods

A prognostic cross-sectional cohort study was conducted involving patients from a single centre who underwent hip arthroscopy between January 2013 and April 2021. Radiological metrics measured on conventional radiographs and magnetic resonance arthrography were systematically assessed. The study analyzed the relationship between these metrics and complication rates, revision rates, and patient-reported outcomes.


Bone & Joint Open
Vol. 3, Issue 10 | Pages 795 - 803
12 Oct 2022
Liechti EF Attinger MC Hecker A Kuonen K Michel A Klenke FM

Aims

Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data.

Methods

We analyzed the FOs measured on AP hip and pelvis radiographs in a prospective consecutive series of 55 patients undergoing unilateral primary THA for hip osteoarthritis. To determine sample size, a power analysis was performed. Patients’ position and X-ray beam setting followed a standardized protocol to achieve reproducible projections. All images were calibrated with the KingMark calibration system. In addition, a geometric model was created to evaluate both the effects of leg position (rotation and abduction/adduction) and the effects of X-ray source position on FO measurement.