Prevalence of Venous Thromboembolism after Immediate Screening in Hip Fracture Patients.

Purpose: Venous thromboembolism (VTE) is a major complication for hip fracture patients, and may exist preoperatively. This study aimed to examine the prevalence of VTE after immediate screening in hip fracture patients. Materials and Methods: Hip fracture patients with an elevated level of D-dimer underwent screening for VTE using computed tomography (CT) angiography. Anticoagulation treatments were administered preoperatively to patients diagnosed with VTE, followed by administration of additional anticoagulation postoperatively. Medical records were reviewed to identify risk factors for preoperative VTE and determine the prognosis of the patients. Results: Among 524 hip fracture patients, 66 patients (12.6%) were diagnosed with VTE, including 42 patients with deep vein thrombosis (DVT), 17 patients with pulmonary thromboembolism (PTE), and 7 patients with both DVT and PTE. Of the patients with VTE, 68.2% were diagnosed within 24 hours of injury, and 33.3% of these patients had PTE. VTE patients showed a tendency toward being overweight (P<0.01) and not on anticoagulant medication (P=0.02) compared to patients without VTE. The risk of VTE was higher for femur shaft fractures (odds ratio [OR] 4.83, 95% confidence interval [CI] 2.18-10.69) and overweight patients (OR 2.12, 95% CI 1.17-3.85), and lower for patients who were previously on anticoagulants (OR 0.36, 95% CI 0.18-0.74). Patients with preoperatively diagnosed VTE were asymptomatic before and after surgery. Conclusion: Clinicians should be aware that VTE may be present within 24 hours of injury, and screening for VTE or prophylactic measures should be considered for high-risk patients.

Outcomes of total hip arthroplasty after failed free vascularized fibular grafting for osteonecrosis of the femoral head.

PURPOSE: Total hip arthroplasty (THA) after vascularized fibular grafting (VFG) is technically demanding with poorer outcomes compared to primary THA in patients with osteonecrosis of the femoral head (ONFH). The purpose of this study was to compare the outcomes of THA after VFG after removal of the graft with that of primary THA. METHODS: ONFH patients treated by VFG at a single institution were studied retrospectively. THAs after VFG performed by single arthroplasty surgeon with a single type of THA prosthesis were enrolled in the study. A control cohort of patients was created by 1:1 matching with the THA after VFG cohort according to age, gender, and American Society of Anesthesiology (ASA) score from ONFH patients treated by primary THA. Early and long-term outcomes were compared between the two groups. RESULTS: A total of 24 hips were included in the THA after VFG group and compared with 24 primary THA hips. No significant difference was noted in stem position. The THA after VFG group had increased blood loss and longer duration of operation time. There were two cases of intraoperative femur fractures in the THA after VFG group. The femoral stem of both groups were stable, with no cases of revision, and similar HHS scores at the last follow-up. CONCLUSION: THA after VFG may have similar short to midterm outcomes with primary THA after removal of the residual abutting bone graft and correct positioning of the femoral stem.

Impact of coronal plane fragments and anterior big neck fragments on the occurrence of perioperative lateral wall fractures in AO/OTA 31-A1,2 intertrochanteric fractures treated with cephalomedullary nailing.

PURPOSE: Cephalomedullary nails are used widely today for pertrochanteric fractures, and intraoperative lateral wall fractures can cause adverse effects. Recently, a high incidence of coronal fragments in pertrochanteric fractures was reported when analyzed with 3D CT reconstructions. In this study, we analyzed the association between the type of coronal fragments and perioperative lateral wall fractures. METHODS: Patients diagnosed with pertrochanteric fractures and treated by cephalomedullary nails at three university hospitals from September 2016 to December 2020 were examined. A total of 463 patients were included. We examined the coronal fragments and divided the patients into two groups according to the involvement of the posteromedial cortex. Postoperative X-rays were scanned for fracture lines at the blade entry site. RESULTS: Twenty-two patients among 463 patients had perioperative lateral wall fractures. The AO type A2 fractures, use of provisional pins, existence of coronal fragments, involvement of the posteromedial cortex, and the existence of anterior big neck fragments were significantly relevant to perioperative lateral wall fractures. 11 of 22 lateral wall fracture patients were delayed fracture patients, identified 4 weeks after surgery. A coronal fragment combined by anterior big neck fragments had a 9.24 times higher risk of lateral wall fractures compared to fractures with only coronal fragments. CONCLUSION: Pertrochanteric fractures with large coronal fragments and anterior big neck fragments have a high risk of perioperative lateral wall fractures when treated by cephalomedullary nails. Surgeons should examine the width of the intact lateral wall, and take caution to preserve its integrity.

Prediction of femoral head avascular necrosis following femoral neck fracture: "pin-tract sign" of 99mTc-HDP pinhole bone scan after metallic fixation.

OBJECTIVE: To evaluate the predicting value of 99mTc-hydroxydiphosphonate (HDP) pinhole bone scan in development of osteonecrosis of femoral head (ONFH) in patients with femoral neck fracture after cannulated screw fixation. METHODS: Pinhole bone scan of patients with metallically fixed femoral neck fracture from 2001 to 2015 were retrospectively reviewed. Initial pinhole bone scan was obtained within 2-3 weeks after surgery. Findings of initial pinhole bone scan were divided in to 4 groups. Group CU included cold defect in affected femoral head, group HU with no cold defect. Group PP with increased uptake along the inserted screws and group PN with no increased uptake along the inserted screws. More than 6 months of follow-up with pinhole bone scan and clinico-radiological evidence for ONFH was reviewed. RESULTS: 72 patients (mean age 54.01 years, male 22, female 50) were included. 19 patients were in group CU, 53 in group HU. 60 patients were in group PP, 12 in group PN. During the follow-up, 13 patients were diagnosed as ONFH. 9 (47.36%) patients in group CU developed ONFH and 4 (7.5%) in group HU. 4 (6.66%) patients in group PP developed ONFH and 9 (75%) in group PN. CONCLUSIONS: To predict ONFH of femoral head followed by neck fracture, many imaging techniques with variable results were known. In this study, cold defect in early postoperative pinhole bone scans could predict ONFH, and loss of increased uptake along screw inserted site could be a strong indicative sign of ONFH. Further evaluation with a larger population is necessary.

Subsidence and perioperative periprosthetic fractures using collarless hydroxyapatite-coated stem for displaced femoral neck fractures according to Dorr type.

BACKGROUND: Hydroxyapatite (HA)-coated stem has been introduced to decrease complications and eventually achieve quicker implant ingrowth and long-term stability. The aim of this study was to determine subsidence rate and incidence of perioperative periprosthetic fracture (PPF) of uncemented collarless Corail stem for displaced femoral neck fractures according to Dorr type. METHODS: A retrospective review of plain radiographs and clinical data was carried out to identify consecutive patients who underwent uncemented hip hemiarthroplasty using collarless HA-coated Corail stem between March 2010 and August 2014. The risk of subsidence and PPF according to Dorr type was evaluated. RESULTS: Dorr types A, B, and C were found in 66 (median age 74, 29.7%), 107 (median age 77, 48.2%), and 49 (median age 80, 22.1%) cases, respectively. Subsidence of stem occurred in eight (3.6%) cases. Dorr type had significant relationship (p < 0.05) with subsidence. Type C canals had higher rates of subsidence. PPFs occurred in 11 (5.0%) cases without showing significant difference among Dorr types not significant (n.s.). Female gender was not influential on subsidence (n.s.) and PPF (n.s.). CONCLUSION: Dorr type C had higher risk of subsidence when using uncemented collarless HA-coated stem. Dorr canal type had no bearing on risk of PPFs. Women did not have significantly higher risk of both subsidence and PPFs compared to men. A collarless fully HA-coated Corail stem had 3.6% of radiological subsidence and 5.0% of PPF risk.

The Frequency of Occult Intertrochanteric Fractures among Individuals with Isolated Greater Trochanteric Fractures.

PURPOSE: Isolated greater trochanteric (GT) fractures are often identified using plain radiography of patients with post-traumatic hip pain. In many cases, the fracture extends to form an occult intertrochanteric fracture. We conducted a study to determine the frequency of occult intertrochanteric fractures in patients diagnosed with isolated GT fractures using plain radiographs. MATERIALS AND METHODS: Among 3,017 individuals who visited our emergency department with a trauma-induced pertrochanteric femur fracture between July 2004 and March 2018, 100 patients diagnosed with isolated GT fractures using plain radiographs were retrospectively analyzed. Patients were divided into two groups, those with: i) isolated GT fractures (group A) and ii) occult intertrochanteric fractures (group B). In addition, plain radiographs, magnetic resonance imaging results, and treatment methods were further analyzed in each group. If surgery treatment was needed, it was performed by one surgeon, and in all cases, a 2-hole dynamic hip screw was used. RESULTS: Among the 100 cases of isolated GT fractures diagnosed using plain radiograph, additional examinations revealed that 10 (10.0%) were suffering from isolated GT fractures alone, while the remaining 90 (90.0%) were further diagnosed with occult intertrochanteric fracture. Gender, age, mechanism of injury, and bone mineral density did not correlate with fracture type. CONCLUSION: In our analysis, 90% of injuries initially diagnosed as isolated GT fractures were found to extend into occult intertrochanteric fractures upon further examination with additional imaging modalities. Therefore, additional evaluation should be performed to test for the potential presence of occult intertrochanteric fractures and to establish appropriate treatment plans.

Is rigid fixation of the greater trochanter necessary for arthroplasty of intertrochanteric fractures?

INTRODUCTION: Stable fixation of the greater trochanter fracture fragments is necessary in arthroplasty of intertrochanteric hip fractures, as nonunion of the greater trochanter fracture comminution may result in impaired function or dysfunction of the abductor lever arm. HYPOTHESIS: The ethibond suture technique is an efficient method for fixation of the greater trochanter fracture fragments. MATERIALS AND METHODS: A total of 47 cases were studied. The mean age of the patients was 80.6 years, and the minimum follow-up was 6 months. Radiologic evaluation was done by examination of greater trochanter healing and measurement of migration of the greater trochanter fragment. Functional evaluation was done by comparison of pre-injury and postoperative ambulation status. RESULTS: The mean migration of the greater trochanter fragment with ethibond sutures was 5.98mm. Union was achieved in 76.6%, and the nonunion rate was 23.4%. 86.9% of patients had no difference in ambulation or had a difference of only 1 level by the Koval score after treatment compared to their pre-injury status. DISCUSSION: The ethibond suture technique provides good fixation of the greater trochanter fragments in arthroplasty of intertrochanteric hip fractures. LEVEL OF EVIDENCE: IV, Case series.

Treatment of Proximal Femur Osteomyelitis Occurred after Proximal Femoral Nail Antirotation Fixation, with Antibiotic Cement-coated Tibia Intramedullary Nail: A Case Report.

Antibiotic cement-coated intramedullary nails maintain a locally high antibiotic concentration while contributing to bone stability. We present a case of femoral subtrochanteric fracture in a patient with an infected nonunion who was successfully treated for an infection and nonunion using an antibiotic cement-coated tibial intramedullary nail. A 79-year-old woman with a right femoral subtrochanteric fracture underwent internal fixation using proximal femoral nail antirotation (PFNA). She developed osteomyelitis with nonunion at the surgical site 10 months postoperatively. We decided to insert an antibiotic cement-coated tibial intramedullary nail. After coating the nail with bone cement mixed with antibiotics, bone fixation was achieved by inserting the nail at the site of the PFNA. The patient's symptoms improved, symptoms from the infection disappeared, and bone union was confirmed. Osteomyelitis occurred because of postoperative infection following a proximal femoral fracture. Antibiotic cement-coated tibial intramedullary nails are an effective option to treat patients with osteomyelitis of the femur and achieve bone union where nonunion persists with shallow a intramedullary femoral canal.

Comparison of Perioperative Blood Loss in Primary Non-cemented Total Hip Arthroplasty for Rapidly Destructive Coxarthrosis and Osteonecrosis of the Femoral Head.

PURPOSE: The purpose of this study is to compare the perioperative blood loss in primary non-cemented total hip arthroplasty (THA) performed for rapidly destructive coxarthrosis (RDC) with the perioperative blood loss in primary non-cemented THA for typical osteonecrosis of the femoral head (ONFH). MATERIALS AND METHODS: From January 2000 to December 2013, 19 patients were diagnosed with RDC (group 1) and 40 patients were diagnosed typical Ficat stage IV ONFH (group 2), comparison of perioperative blood loss between group 1 and group 2 in primary noncemented THA was done. Patients with preoperative usage of steroid or anticoagulants medication and with hemodynamic abnormal blood test results were excluded. The blood loss was measured up to the fifth post operation day and calculated with formula proposed by Mercuriali, Inghilleri and Nadler. RESULTS: Non-compensated blood loss calculated in milliliters of red blood cells was 362 mL (standard deviation [SD], 187; range, 77-675) in group 1 and 180 mL (SD, 145; range, 53-519) in group 2. Compensated blood loss was 630 mL (SD, 180; range, 380-760) in group 1 and 503 mL (SD, 260; range, 190-1, 505) in group 2. The total blood loss after primary non-cemented THA is greater when surgery is performed for RDC than for ONFH, with the volume of 992 mL (SD, 300; range, 457-1, 434) in group 1 and 683 mL (SD, 360; range, 226-1, 975) in group 2 respectively. CONCLUSION: Total perioperative blood loss was significantly greater in RDC than in ONFH in primary non-cemented THA.

Incidence and risk factors of subsequent hip fractures in Korea: multicenter study.

This study analyzes the incidence of subsequent hip fractures and its risk factors in the northwestern region of Korea. We analyzed hip fracture patients who visited any of the 5 teaching hospitals in the Bucheon and Incheon area from January 2000 to December 2010. Medical records were reviewed and presence of subsequent hip fractures, alcohol history, marital status, live in solitude, dementia, dizziness, American society of anesthesiologists score, osteoporosis treatment after fracture, body mass index (BMI) and initial bone mineral density were analyzed. The average follow-up period was 12 months (range 1-130 months). A total of 2,546 patients (women 1,770, men 776) who had experienced hip fractures were included. Of these, subsequent hip fractures were found in 233 patients (9.2%) (women 187, men 46). Mean age at the time of the first fracture was 79.2 yr old (range 50-100 yr). The average interval between the first fracture and the subsequent hip fractures was 30.2 months (range 4 days-154 months). In this large-scale, retrospective, multicenter study, overall incidence of subsequent hip fractures is 9.2%. Independent risk factors of subsequent fracture are women, BMI<22 kg/m(2), and being unmarried.

Atypical femoral fractures after anti-osteoporotic medication: a Korean multicenter study.

PURPOSE: Increasing numbers of atypical femoral fractures have been reported among long-term bisphosphonate users. We evaluated clinical characteristics of atypical femoral fractures throughout Korean multicenter studies. METHODS: We retrospectively analysed the bone mineral density, prodromal symptoms before femoral fracture, and medication history of osteoporosis in 76 cases of atypical femoral fracture. RESULTS: The mean age of cases was 71.4 ± 8.8 (range, 43-89) years old. The mean follow-up period after the fracture operation was 24.5 ± 12.9 (range, 12-79) months. BMI was 23.2 ± 3.0 on average. The mean BMD of femur was -1.9 ± 1.4 (range, -4.8 to 1.3). Prodromal symptoms including thigh pain before femoral fracture appeared in 22 (28.9 %) of 76 patients. All patients included in the study used bisphosphonate. The duration of taking bisphosphonate before fracture was 36.8 ± 50.8 (one-204 months) months. Fifty-seven (75 %) of 76 patients were taking the medication for more than three years. Delayed union occurred in 43 (56.5 %) of 76 patients. Delayed union was defined as a fractured bone that did not completely heal within six months of injury. The group of having taken anti-osteoporotic medication for more than three years showed relatively longer union period compared to that for a shorter period medication group (4.8 ± 2.5 months vs 9.3 ± 3.7 months, p = 0.017). The delayed union developed in 43 (56.5 %) of 76 patients and showed a significantly higher incidence in the group with long-term therapy (five/43 vs 38/43, p = 0.021). The bilateral femoral fractures developed in 23 (30.2 %) of 76 patients and showed a high incidence in the group medicated more than three years (two/23 vs 21/23, p = 0.039). CONCLUSIONS: The longer bisphosphonates are used, the more the cases of delayed union and the more frequent the development of bilateral fractures following unilateral fractures. With regard to the delayed union, the methods of the acceleration of fracture healing may be beneficial in atypical femoral fracture patients who had been receiving long-term bisphosphonates therapy. Careful observation is required for contra-lateral femurs due to a high incidence of bilateral atypical femoral fractures.

Retaining well-fixed cementless stem in the treatment of infected hip arthroplasty.

BACKGROUND AND PURPOSE: Two-stage reconstruction, reimplantation after removal of an infected prosthesis, has been considered to be the gold standard for treatment of infected hip arthroplasty. However, during the removal of a well-fixed femoral stem, the proximal femur can be damaged and a sequestrum can be formed, which might lead to chronic osteomyelitis and difficulty in reimplantation. We wanted to determine whether infection after hip arthroplasty can be treated without removal of a well-fixed stem. METHODS: We treated 19 patients who had an infection after hip replacement, but a well-fixed cementless stem, with 2-stage reconstruction. At the first stage, we removed the acetabular cup, the liner and the head, but not the stem. We then implanted a cup of cement spacer. After control of infection, we reimplanted the acetabular component and head. RESULTS: 2 patients did not undergo second-stage reconstruction because they were satisfied with the pain relief and the activity that they had with the cement-spacer implantation. The remaining 17 patients underwent the second-stage of the reconstruction using cementless arthroplasty. At a mean follow-up time of 4 (2-8) years, 15 of the patients had no recurrence of infection, with satisfactory clinical and radiographic outcome. INTERPRETATION: This second-stage reconstruction after retention of the stem could be an alternative treatment option for periprosthetic infection with a well-fixed stem.

Emphasis on the MR imaging findings of brown tumor: a report of five cases.

OBJECTIVE: Brown tumors are focal reactive osteolytic lesions that are encountered in patients with primary or secondary hyperparathyroidism, and these tumors have nonspecific magnetic resonance (MR) imaging findings. However, there are only a few reports on MR imaging of brown tumors. The purpose of this study is to describe the spectrum of MR imaging findings of brown tumors. MATERIALS AND METHODS: The MR imaging features of five patients with clinical and pathological evidence of brown tumor were retrospectively reviewed by two radiologists. The patients had primary hyperparathyroidism, which was confirmed as parathyroid adenoma (n = 2) and parathyroid carcinoma (n = 3). The MR images were evaluated for the presence of solid or cystic portions, the signal intensity of the lesions, the contrast enhancement pattern and the presence of cortex destruction and fluid-fluid levels. RESULTS: Twelve bone lesions were detected on the MR images of five patients; three lesions in two patients, four lesions in one patient, and one lesion in two patients. The tumor was solid in three lesions, mixed solid and cystic in four, and cystic in five. All the solid lesions were accompanied by mixed lesions. Discontinuity of the cortex and adjacent soft-tissue enhancement were seen in all the solid lesions. Fluid-fluid levels were seen in two cases within the cystic component of the mixed lesions and cystic lesions. CONCLUSIONS: The five patients with brown tumor demonstrated a wide spectrum of MR imaging findings. There are few lesions that are osteolytic on the radiographs and that show a short T2 on MR imaging, such as brown tumor. Multiple cystic or mixed lesions are the expected findings of brown tumors.

Isolated fractures of the greater trochanter with occult intertrochanteric extension.

INTRODUCTION: Isolated fractures of the greater trochanter (GT) are relatively rare. The diagnosis can be done on routine radiographs, but it is difficult to fully define the geographic extent of these injuries. This study examined the pattern and extent of an injury shown by magnetic resonance imaging (MRI) and radionuclide bone scan (RBS) in patients whose plain radiographs revealed fractures limited to the GT. MATERIALS AND METHODS: Between July 2004 and October 2008, 25 patients who displayed an isolated GT fracture on plain radiograph examination were examined by both MRI and RBS due to a suspicion of an extension into the intertrochanteric (ITC) region. The patients were then divided into two groups. Group A patients had an isolated fracture of GT, and group B patients had an occult fracture of ITC. RESULTS: All 25 cases were caused by a low-energy injury and plain radiographs showed non-displaced or minimally displaced isolated GT fractures. For 22 of the 25 patients, the result agreed with MRI and RBS. However, three patients had focal increased uptake at the GT region only according to RBS and an extension of signal intensity into the ITC region according to MRI. Group A and B comprised 5 and 20 patients, respectively. Of the group B patients, 8 had fractures with MRI evidence of complete extension across the ITC region and 12 had incomplete extension. Eleven of the 12 incomplete types showed an extension more than half way to the medial cortex. Fifteen group B patients underwent an internal fixation using a two-hole dynamic hip screw. CONCLUSION: Patients with an isolated fracture of GT can have a broader fracture extending into the ITC region than that diagnosed by standard radiographs. We recommend that all patients presenting with an isolated GT fracture on the plain radiographs should undergo MRI examination.

Development of Korean Academy of Medical Sciences Guideline rating the physical impairment: lower extremities.

Lower Extremities Committee of Korean Academy of Medical Sciences Guideline for Impairment Rating develops new guidelines which are based on McBride method, American Medical Association Guides, Disability evaluation by The Korean Orthopaedic Association, The Korean Neurosurgery Society, and Korean Academy of Rehabilitation Medicine. The committee analyzed and discussed to create an ideal method practical in Korea. Our committee endeavors to develop new methods which are easy to use, but are suitable for professional use and also independent from the examinee's intentions. The lower extremities are evaluated on the basis of anatomic change, functional change, and diagnosis based evaluation. Nine methods are used to assess the lower extremities. Anatomic assessment includes leg length discrepancy, ankylosis, amputation, skin loss, peripheral nerve injury, and vascular disease. In functional assessment, range of motion and muscle strength are included. Diagnosis-based assessments are used to evaluate impairment caused by specific fractures, deformities, ligament instability, meniscectomies, post-traumatic arthritis, fusion of the foot, and lower extremity joint replacements.

Subtrochanteric fracture after free vascularised fibular grafting for osteonecrosis of the femoral head.

The aim of this study was to determine the incidence and factors associated with subtrochanteric fracture after free vascularised fibular grafting for osteonecrosis of the femoral head, and to analyse clinical and radiological outcomes of open reduction and internal fixation. From April 1991 to May 2004, eight such fractures were managed by Rowe plate fixation. Factors examined included age, gender, side of operation, cause and preoperative and postoperative stage of osteonecrosis, and preoperative and postoperative functional assessment. The osteonecrosis was caused by alcohol consumption in six, steroid use in one and was idiopathic in one case. The overall incidence of fracture was 4.1% (13.9% in bilateral operations) and all occurred in men of mean age 36.3 years, were induced by low-energy injury and were attributed to defects created in the lateral femoral cortex for graft placement. Seven of the eight fractures (87.5%) developed within 12 weeks and all fractures healed at a mean of 16.6 weeks after internal fixation. No major complications occurred and no significant differences were found in clinical or radiological results between the fracture and non-fracture groups. Our findings indicate that strict education and mandatory protection from full weight bearing are required for 12 weeks after free vascularised fibular grafting for osteonecrosis of the femoral head.

The biomechanical results of total hip resurfacing arthroplasty.

BACKGROUND: With the advent of more wear-resistant bearings, there is renewed interest in resurfacing total hip arthroplasty. However, there is a paucity of information on the biomechanical results of this type of arthroplasty compared with those of contemporary total hip arthroplasty. METHODS: Using standardized radiographs, we measured and compared the biomechanical parameters that affect the hip joint reactive forces in fifty hips that had a metal-metal surface replacement with those parameters in forty hips that had a contemporary cementless total hip replacement performed during the same time-period by the same surgeon. RESULTS: On the average, the arthritic hips that were treated with metal-metal surface replacement had had a more valgus preoperative neck-shaft angle and less horizontal femoral offset than the normal, contralateral hips (p = 0.0003). After both the metal-metal surface replacements and the cementless total hip replacements, the hip center of rotation was medialized by approximately 6 mm. Both procedures were associated with an average increase in limb length of approximately 3 or 4 mm. After the metal-metal surface replacements, the horizontal femoral offset was essentially equal to the preoperative value, but both values averaged about 8 mm less than those on the normal, contralateral side (p < 0.00001). In the hips with a conventional total hip replacement, the horizontal femoral offset increased an average of 9.5 mm compared with the preoperative value and was an average of 5 mm more than that for the normal, contralateral hip (p = 0.001). CONCLUSIONS: The biomechanical results of total hip resurfacing depend on the preoperative anatomy of the proximal part of the femur. Limb lengthening of 1 cm can be achieved, but horizontal femoral offset is essentially unchanged by hip resurfacing. Horizontal femoral offset can be increased reliably with a contemporary total hip replacement. Arthritic hips of limbs that are more than 1 cm shorter than the contralateral limb or that have a comparatively low horizontal femoral offset may be better served by a contemporary total hip replacement. These biomechanical limitations should be considered in the selection of hips for resurfacing. LEVEL OF EVIDENCE: Therapeutic study, Level III-1 (case-control study). See Instructions to Authors for a complete description of levels of evidence.