Novel susceptibility loci for steroid-associated osteonecrosis of the femoral head in systemic lupus erythematosus.

Osteonecrosis of the femoral head (ONFH) involves necrosis of bone and bone marrow of the femoral head caused by ischemia with unknown etiology. Previous genetic studies on ONFH failed to produce consistent results, presumably because ONFH has various causes with different genetic backgrounds and the underlying diseases confounded the associations. Steroid-associated ONFH (S-ONFH) accounts for one-half of all ONFH, and systemic lupus erythematosus (SLE) is a representative disease underlying S-ONFH. We performed a genome-wide association study (GWAS) to identify genetic risk factors for S-ONFH in patients with SLE. We conducted a two-staged GWAS on 636 SLE patients with S-ONFH and 95 588 non-SLE controls. Among the novel loci identified, we determined S-ONFH-specific loci by comparing allele frequencies between SLE patients without S-ONFH and non-SLE controls. We also used Korean datasets comprising 148 S-ONFH cases and 37 015 controls to assess overall significance. We evaluated the functional annotations of significant variants by in silico analyses. The Japanese GWAS identified 4 significant loci together with 12 known SLE susceptibility loci. The four significant variants showed comparable effect sizes on S-ONFH compared with SLE controls and non-SLE controls. Three of the four loci, MIR4293/MIR1265 [odds ratio (OR) = 1.99, P-value = 1.1 × 10-9)], TRIM49/NAALAD2 (OR = 1.65, P-value = 4.8 × 10-8) and MYO16 (OR = 3.91, P-value = 4.9 × 10-10), showed significant associations in the meta-analysis with Korean datasets. Bioinformatics analyses identified MIR4293, NAALAD2 and MYO16 as candidate causal genes. MIR4293 regulates a PPARG-related adipogenesis pathway relevant to S-ONFH. We identified three novel susceptibility loci for S-ONFH in SLE.

Progressive Bone Destruction in Rapidly Destructive Coxopathy Is Characterized by Elevated Serum Levels of Matrix Metalloprotease-3 and C-Reactive Protein.

OBJECTIVE: Rapidly destructive coxopathy (RDC) is a rare condition characterized by rapid joint space narrowing; however, its pathology remains unclear. This study aimed to clarify the association of laboratory biomarkers with the radiological progression of RDC. METHODS: We examined 34 female and 4 male patients with RDC between October 2010 and April 2018. Patients were divided into 3 groups according to the progressive radiographic staging of RDC. Group 1 patients had progressive obliteration of the joint space without subchondral destruction (n = 11), group 2 had progressed subchondral destruction (n = 18), and group 3 had cessation of bone destruction observed for more than 6 months (n = 9). Clinical evaluation results were assessed using the Japanese Orthopedic Association hip score. Blood test results, including serum matrix metalloproteinase-3 (MMP-3), and C-reactive protein (CRP), were also evaluated. RESULTS: There were no significant differences in patient background or Japanese Orthopedic Association hip scores among the groups. However, there were significant differences in MMP-3 levels among groups, with MMP-3 levels in group 2 being significantly higher than those in group 3 (group 2, 118.4 ± 81.2 ng/mL; group 3, 42.5 ± 15.1 ng/mL, p < 0.001). The CRP levels in group 2 were also significantly higher than those in group 3 (group 2, 0.77 ± 0.92 mg/dL; group 3, 0.13 ± 0.07 mg/dL, p = 0.019), but elevated CRP levels in group 2 decreased back to the reference range. CONCLUSIONS: Matrix metalloproteinase-3 and CRP are the biomarkers of RDC progression but not of its occurrence. Severe inflammatory response may be associated with bone destruction in RDC.

Long-term results of Birmingham hip resurfacing arthroplasty in Asian patients.

Several reports have shown good long-term results with the Birmingham hip resurfacing (BHR) arthroplasty, but little is known about the results in Asian countries where there is a high prevalence of osteonecrosis and developmental dysplasia of the hip, and many females with small femoral head sizes. Therefore, we retrospectively evaluated the long-term clinical results of the BHR in 112 Japanese patients (53 males and 59 females-130 hips) with an average age of 52 years. Implant survivorship was analyzed using the Kaplan-Meier method with the endpoint being revision for any reason. Factors such as sex, femoral component size, and type of hip disease were analyzed as predictors of implant survivorship. With a median follow-up of 12 years, six cases were revised (two for femoral component aseptic loosening, two for infection, one for cup aseptic loosening, and one for femoral neck fracture), and the overall survival rate was 96.5% (95% CI 90.9-98.7) at 10 years and 93.6% (95% CI 83.4-97.7) at 15 years. When septic revisions were excluded, the implant survival rate was 98.2% (95% CI 92.9-99.6) at 10 years and 95.3% (95% CI 83.9-98.7) at 15 years. Sex, femoral component size, and type of hip disease were not predictors of implant survivorship. In conclusion, good clinical results were obtained with the BHR at 10- and 15-year follow-up in Japanese patients who have different stature and types of hip diseases as compared with patients in Western countries.

Outcome of anatomical double-bundle ACL reconstruction using hamstring tendons via an outside-in approach.

PURPOSE: To evaluate the clinical outcome of anatomical double-bundle anterior cruciate ligament (ACL) reconstruction using multistranded hamstring tendons via an outside-in approach. METHODS: One hundred and twenty-one patients (mean age 28 ± 10 years) who underwent ACL reconstruction were examined. Using an outside-in femoral drill guide, an upper femoral tunnel for the anteromedial (AM) graft was created just below the superior articular cartilage margin of the medial wall of the lateral condyle through a small incision. A lower femoral tunnel for the posterolateral (PL) graft was drilled in the centre of the inferior-posterior half of the attachment area behind the resident's ridge in the same manner. Two tibial tunnels were created at the centre of the AM and PL bundle footprints of a normal ACL. Patients were evaluated at 24 months postoperatively. RESULTS: According to the IKDC form, 52 knees (43 %) were graded as normal, 64 (53 %) as nearly normal, 1 (1 %) as abnormal and 4 (3 %) as graft rupture due to re-injury. Loss of knee extension of <5° was observed in one patient (1 %). Among 111 patients who were directly evaluated, none showed loss of flexion of <5°. Lachman sign was negative in 103 patients (93 %), while the pivot shift test result was negative or equivalent to that of the contralateral healthy knee in 103 patients (93 %). The mean side-to-side difference in anterior laxity at manual maximum force with the KT-2000 arthrometer(®) was 0.9 ± 1.1 mm, and 94 % of patients showed a range between -1 and +2 mm. CONCLUSION: The anatomical double-bundle outside-in ACL reconstruction provided a satisfactory short-term outcome. LEVEL OF EVIDENCE: Case series, Level IV.

[A case of recurrent duodenal gastrointestinal stromal tumor resistant to imatinib and sunitinib, successfully treated with regorafenib].

Regorafenib is a novel, orally administered multi-kinase inhibitor that has recently been approved for the treatment of recurrent gastrointestinal stromal tumor (GIST). We report a case of successful treatment of recurrent duodenal GIST, which was found to be resistant to imatinib and sunitinib, with regorafenib. A 62-year-old woman underwent a pancreatoduodenectomy for duodenal GIST; after 2 years, a computed tomography (CT) scan detected liver metastases. The patient received imatinib for 6 years, and underwent 2 hepatectomies. Subsequently, she received sunitinib for 10 months; however, CT scans revealed the presence of multiple vertebral metastases. She underwent a laminectomy for the palliative treatment of the vertebral metastases. Upon immunohistochemical examination, the recurrent tumor stained positive for c-kit, confirming the diagnosis for GIST. Consequently, the patient received regorafenib; although the treatment controlled the liver metastases, the vertebral metastases were found to have progressed. She survived for 9 years and 5 months after the initial surgical resection. Regorafenib might be beneficial in the treatment of recurrent GISTs that prove to be resistant to imatinib and sunitinib.

Time elapsed from definitive diagnosis to surgery for osteonecrosis of the femoral head: a nationwide observational study in Japan.

OBJECTIVES: This study documents the time elapsed from the diagnosis of osteonecrosis of the femoral head (ONFH) to surgery, exploring the factors that influence ONFH severity. DESIGN: Retrospective observational study of a nationwide database. SETTING: The Kaplan-Meier method with log-rank tests was applied to examine the period from definitive diagnosis of ONFH to surgery using any surgery as the end point. For bilateral cases, the date of the first surgery was the endpoint. PARTICIPANTS: This study included 2074 ONFH cases registered in 34 university hospitals and highly specialised hospitals of the multicentre sentinel monitoring system of the Japanese Investigation Committee between 1997 and 2018. MAIN OUTCOME MEASURE: The primary outcome was the time from diagnosis to surgery. The secondary outcome was the proportion of subjects remaining without surgery at 3, 6 and 9 months, and at 1, 2 and 5 years after diagnosis. RESULTS: The median time to surgery was 9 months (IQR 4-22 months) after diagnosis of ONFH. The time to surgery was significantly shorter in the alcohol alone group and the combined corticosteroid and alcohol group than in the corticosteroid alone group (p=0.018 and p<0.001, respectively), in early stage ONFH with no or mild joint destruction (stages II and III, p<0.001), and with joint preserving surgery (p<0.001). The proportion without surgery was 75.8% at 3 months, 59.6% at 6 months, 48.2% at 9 months, 40.5% at 1 year, 22.2% at 2 years and 8.3% at 5 years. CONCLUSION: ONFH has been considered to be an intractable disease that often requires surgical treatment, but the fact that surgery was performed in more than half of the patients within 9 months from diagnosis suggests severe disease with a significant clinical impact. TRIAL REGISTRATION NUMBER: Chiba University ID1049.

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up.

PURPOSE: Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases. METHODS: We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips). RESULTS: Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening. CONCLUSIONS: The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.

High survival of dome pelvic osteotomy in patients with early osteoarthritis from hip dysplasia.

BACKGROUND: The Chiari osteotomy reportedly has a 60% to 91% survival rate at a minimum 20 years followup. The dome pelvic osteotomy (DPO) has the advantage of allowing a larger weightbearing surface, and congruity in the sagittal plane presumably would reduce the joint contact stress and perhaps increase longevity. QUESTIONS/PURPOSES: We determined: (1) the survival after DPO at a minimum 25-year followup, (2) patient function, (3) acetabular coverage, and (4) factors influencing conversion to THA. METHODS: We retrospectively reviewed 50 patients (59 hips) with developmental dysplasia of the hip (DDH) treated with DPO. The preoperative radiographic stages were graded as prearthritis (18 hips), early osteoarthritis (25 hips), and advanced osteoarthritis (16 hips). We performed a Kaplan-Meier survival analysis with THA conversion as the end point. We determined various radiographic parameters reflecting coverage, and compared demographic information for hips without and with THA conversion using multivariate logistic regression analysis. The minimum followup was 25 years (mean, 27.5 years; range, 25-32 years). RESULTS: Survival for all hips was 63.6% (95% CI, 51-76) at 27.5 years and that for hips with prearthritis and early osteoarthritis before the surgery was 79.1% (95% CI, 63-91). Twenty-one hips (36%) had undergone THAs at a mean 18.3 years (range, 2.5-25 years). At the last followup, pain, walking ability, and acetabular coverage improved. We identified four factors predicting THA conversion: greater age, presence of a preoperative Trendelenburg sign, higher preoperative radiographic osteoarthritis grade, and smaller postoperative acetabular head index (AHI) predicted conversion to THA. CONCLUSIONS: DPO is a reasonable treatment option for patients with DDH and prearthritis or early osteoarthritis, with high survival at greater than 25 years.

Anterior impingement test for labral lesions has high positive predictive value.

BACKGROUND: The anterior impingement test is intended to detect anterosuperior acetabular labral lesions. In patients treated for labral lesions its sensitivity is reportedly 95% to 100%, and in a small group of patients undergoing periacetabular osteotomy, its sensitivity was 59% and specificity 100%. However, the sensitivity, specificity, positive predictive value, and negative predict value of this test to detect these labral lesions in unselected patients with hip pain are unknown. QUESTIONS/PURPOSES: We investigated these four parameters (1) in unselected patients with hip pain, and (2) in three subgroups of patients with dysplasia, femoroacetabular impingement (FAI), and with an intact joint space. METHODS: We prospectively studied 69 patients (15 men and 54 women) with a mean age of 57.2 years (range, 27-81 years). One observer performed the anterior impingement test in all patients. We determined the presence or absence of an anterosuperior labral lesion with radial MRI in 107 hips (38 patients in both hips: 14 with pain, and 24 without pain). We also investigated the parameters in the three subgroups which consisted of 60 cases of dysplasia, 27 cases of FAI, and 80 cases with intact joint space; the third subgroup partially overlapped the first and second subgroups. RESULTS: The four parameters in all hips were 50.6% (45/89), 88.9% (16/18), 95.7% (45/47), and 26.7% (16/60), respectively. Parameters in the three subgroups were similar to those of all cases. CONCLUSIONS: Although the sensitivity of the anterior impingement test did not reach a sufficient level for detecting anterosuperior labral lesions, we believe the high positive predictive value makes the test useful. LEVEL OF EVIDENCE: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Eleven- to 14-year follow-up results of cementless total hip arthroplasty using a third-generation alumina ceramic-on-ceramic bearing.

To analyze long-term survivorship of cementless total hip arthroplasties (THAs) with the third-generation alumina ceramic-on-ceramic bearing, 100 consecutive THAs between 1996 and 1998 were reviewed. One cup and 2 stems were revised due to aseptic loosening. Another cup showed chipping of the acetabular liner at 8 years and required cup revision. The remaining hips showed stable bone ingrowth fixation with no osteolysis at the final follow-up. The 14-year survivorship as the end point of revision was 97.9% for the cup, 97.8% for the stem, and 95.7% for the overall implants, respectively. We conclude that cementless THA with the third-generation ceramic-on-ceramic hip bearing provided an excellent survivorship and eliminated periprosthetic osteolysis for 11 to 14 years.

Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ): a patient-based evaluation tool for hip-joint disease. The Subcommittee on Hip Disease Evaluation of the Clinical Outcome Committee of the Japanese Orthopaedic Association.

BACKGROUND: The Japanese Orthopaedic Association Hip Score is widely used in Japan, but this tool is designed to reflect the viewpoint of health-care providers rather than that of patients. In gauging the effect of medical therapies in addition to clinical results, it is necessary to assess quality of life (QOL) from the viewpoint of patients. However, there is no tool evaluating QOL for Japanese patients with hip-joint disease. METHODS: With the aim of more accurately classifying QOL for Japanese patients with hip-joint disease, we prepared a questionnaire with 58 items for the survey derived from 464 opinions obtained from approximately 100 Japanese patients with hip-joint disease and previously devised evaluation criteria. In the survey, we collected information on 501 cases, and 402 were subjected to factor analysis. From this, we formulated three categories-movement, mental, and pain-each comprising 7 items, for a total of 21 items to be used as evaluation criteria for hip-joint function. RESULTS: The Cronbach's α coefficients for the three categories were 0.93, 0.93, and 0.95, respectively, indicating the high reliability of the evaluation criteria. The 21 items included some related to the Asian lifestyle, such as use of a Japanese-style toilet and rising from the floor, which are not included in other evaluation tools. CONCLUSIONS: This self-administered questionnaire may become a useful tool in the evaluation of not only Japanese patients, but also of members of other ethnic groups who engage in deep flexion of the hip joint during daily activities.

The results of a press-fit-only technique for acetabular fixation in hip dysplasia.

The purpose of the present study was to evaluate the 6- to 11-year follow-up results of hemispherical porous-coated cups implanted into dysplastic hips using press-fit technique without screws focusing on the amount of host bone coverage. There were 87 patients who underwent 98 primary total hip arthroplasties. Bony coverage was measured as the angle between the vertical line and the line drawn from the cup center to the lateral edge of the acetabulum, which was named the cup center-edge angle (cup-CE angle). All 98 cups were judged to be bone ingrown. The minimum cup-CE angle was 8.4° (mean, 26.3°). Bone-cup contact of more than 8.4° of the cup-CE angle was large enough for press-fit cups to resist superior directed loads during this follow-up period.

Are acetabular component alignment guides for total hip arthroplasty accurate?

The acetabular component orientation of total hip arthroplasty is of critical importance to the clinical results. Although navigation systems have recently been introduced, acetabular component alignment guides are still used in most of ordinary hospitals. However, the accuracy of alignment guides themselves has not been evaluated. Fifteen types of alignment guide were examined. In all the alignment guides, the angles actually indicated and those stated by manufacturers were different. Our results showed that usage of modern alignment guides inherently misleads anteversion into decrease by a mean of 6 degrees (maximum, 12 degrees ) and inclination into increase by a mean of 2 degrees (maximum: 4 degrees ). Such setting of alignment guides could be one of the factors of error in acetabular component orientation.

The vascular network in the femoral head and neck after hip resurfacing.

The purpose of this study was to determine whether femoral neck fracture after cemented resurfacing hip arthroplasty (RHA) arises from intraosseous vascularity around the femoral head-neck junction. We implanted a replica of the femoral head component into osteoarthritic femoral heads and compared the intraosseous vascularity network between the femoral heads with and without the RHA procedure using microangiography through a retinacular artery with micro-computed tomography. Our results showed no significant difference in the vascularity around the femoral head-neck junction between the groups with and without the RHA procedure. These results suggest that deterioration of the intraosseous vascular network around the head-neck junction after RHA was not severe enough to induce complete avascularity.

Outcome of double-bundle ACL reconstruction using hamstring tendons.

The objective of this article is to describe the clinical outcome of the transitional double-bundle procedure for anatomical ACL reconstruction. Subjects included 78 patients (average age 25 years) who had undergone ACL reconstruction with the transitional double-bundle procedure with multi-stranded hamstring tendons. The femoral socket for the anteromedial (AM) graft was created at 5-6 mm from the mid-sagittal line of the intercondylar notch at 2:00 or 10:00, and that for the posterolateral (PL) graft was drilled adjacent to the AM socket at 3:00 or 9:00. For the tibial side, two tunnels were made at the center of the footprint of the AM and PL bundles of the normal ACL. Patients were evaluated at 24 months or longer postoperatively based on the IKDC Knee Examination Form. Subjectively, 32 knees (41%) were graded as normal; 41 (53%), as nearly normal; 4 (5%), as abnormal; and 1 (1%) as graft rupture by re-injury. The average side-to-side difference in anterior laxity at manual maximum force with the KT-2000 arthrometer was 0.9 mm +/- 1.2. Seventy patients (93%) had a range between -1 mm and 2 mm. In conclusion the transitional double-bundle ACL reconstruction provided a satisfactory outcome after a short-term follow-up.

Range of motion of standard and high-flexion cruciate retaining total knee prostheses.

Recently, use of high-flexion design was introduced in cruciate-retaining (CR) total knee prostheses. The purpose of this study was to prospectively compare the ranges of motion (ROMs) of 89 knees with standard and 87 knees with high-flexion CR total knee prostheses. Differences in age, gender, diagnosis, preoperative ROM of the knee, and Knee Society Score between the 2 groups were not statistically significant. At 12-month follow-up, average ROM was 112.0 degrees +/- 12.6 degrees for standard, and 115.3 degrees +/- 13.4 degrees for high-flexion CR prosthesis (P = .101). To our knowledge, this is the first report on the ROM with the high-flexion CR total knee prosthesis. Using the technique of anterior referencing for femoral component sizing and using a fixed 7 degrees slope for the tibial component, we found no significant differences between groups with regard to ROM, clinical, or radiographic parameters.

Clinical efficacy of mechanical thromboprophylaxis without anticoagulant drugs for elective hip surgery in an Asian population.

To evaluate the clinical efficacy of mechanical thromboprophylaxis after elective hip surgery, we reviewed 3016 patients who underwent hip surgery at 5 centers. Primary total hip arthroplasty (THA), revision THA, and pelvic or femoral osteotomies were performed in 2648, 298, and 70 patients, respectively. Epidural anesthesia, intraoperative calf bandage, early mobilization, and intermittent pneumatic compression postoperatively with additional use of elastic stockings were the basic regimen for thromboprophylaxis. Postoperatively, no cases of fatal pulmonary embolism (PE) were encountered. One symptomatic PE and 4 symptomatic deep vein thrombosis cases were identified, all of which were successfully treated using heparin and warfarin. By 6 months, no deaths had occurred. We conclude that mechanical thromboprophylaxis without anticoagulant drugs is safe and effective for elective hip surgeries in our patient population.

Acetabular component orientation in intra- and postoperative positions in total hip arthroplasty.

INTRODUCTION: In total hip arthroplasty (THA), acetabular component orientation has critically important effects on dislocation, range of motion, polyethylene wear, pelvic osteolysis, and component migration. The differences in the pelvic orientation in the intraoperative lateral position for insertion of acetabular component during operation and that in the postoperative supine position for evaluation of acetabular component orientation will be one of the factors, which make outliers in acetabular component orientation. We compared acetabular component orientation between intraoperative lateral position and postoperative supine position in 100 consecutive primary THAs. MATERIALS AND METHODS: A total of 100 consecutive primary THAs (between October 2004 and December 2005) in 100 patients performed by a single surgical team were investigated. Intraoperative anteroposterior radiographs of pelvis in the lateral position and postoperative anteroposterior radiographs of pelvis in the supine position were taken. Acetabular component orientation (vertical tilt and anteversion) were measured using computer software. RESULTS: The absolute values of difference between measurements in the two positions were 5.3 degrees +/- 4.5 degrees (mean +/- SD) for vertical tilt and 5.1 degrees +/- 3.7 degrees for anteversion. The difference in the vertical tilt between the two positions was significant (P < 0.0001). CONCLUSION: The difference in the acetabular component orientation between the two positions, which might be caused by the difference between intra- and postoperative pelvic orientation, should be considered during THA.

Immunoglobulin G4-Related Disease of the Hip.

The authors report a case of immunoglobulin G4-related disease (IgG4-RD) of the hip. A 60-year-old man diagnosed with osteoarthritis of the right hip was referred to the authors' outpatient clinic for surgical intervention. Laboratory test results revealed elevated C-reactive protein and serum IgG levels. A subsequent laboratory test revealed an IgG4 level of 318 mg/dL. Magnetic resonance imaging revealed an abnormal mass in the right hip joint. The authors suspected IgG4-RD of the hip. The mass was resected during total hip arthroplasty. Immunohistochemical analysis for IgG revealed positive staining of many plasma cells. Most of the IgG-positive plasma cells were positive for IgG4, and the ratio of IgG4/IgG-positive cells was 51%. This case met all criteria for IgG4-RD; thus, the authors made a definitive diagnosis of IgG4-RD of the hip. The C-reactive protein level decreased to a negative value, and the IgG level decreased to a normal range at 3 weeks postoperatively. The IgG4 level gradually decreased to 152 mg/dL at 5 months postoperatively. This is the first reported case of IgG4-RD of the hip joint. [Orthopedics. 2018; 41(6):e876-e879.].

[Diagnostic criteria, staging system and classification of idiopathic osteonecrosis of the femoral head].

Five criteria which showed high specificity were selected as follows. 1) collapse of the femoral head or crescent sign, 2) demarcating sclelosis in the femoral head, 3) cold in hot in bone scan, 4) band -like pattern on T1 weighted image of magnetic resonance imaging (MRI) , 5) trabecular and marrow necrosis on histology. Definite idiopathic osteonecrosis of the femoral head (ION) is diagnosed by fulfilling any two of the five criteria. Staging is judged on both AP and lateral X-ray. Stage 1 is defined as a period of no abnormality on X-ray. Stage 2is a period of demarcating sclelosis seen in X-ray. Stage 3 is a period of collapse of the head. Stage 3 is subclassified into Stage 3A when collapse is less than 3mm and 3B when collapse is 3mm or more. Stage 4 is a period of osteoarthritic changes. According to location of necrotic lesion on T1 weighted images or on x-ray, the lesions are classified into into four types. Type A lesion is defined to occupy medial one third or less of weight bearing portion. Type B lesion is defined to occupy medial two third or less of weight bearing surface. Type C1 lesion is defined to occupy more than medial two third, but not beyond acetabular edge while Type C2 lesion is defined to extend lateral to the acetabular edge.