Three-dimensional femur morphology analysis for the optimal location of subtrochanteric osteotomy with an implanted Wagner cone stem in total hip arthroplasty for Crowe type IV developmental dysplasia of the hip.

BACKGROUND: This study aimed to accurately evaluate the matching of proximal and distal femoral segments and fitting of the femur-femoral stem in patients with Crowe type IV developmental dysplasia of the hip (DDH) who have undergone subtrochanteric osteotomy at different locations with an implanted Wagner cone stem to improve the rate of the bone union at the osteotomy site. METHODS: Three-dimensional femur morphology of 40 patients with Crowe type IV DDH was evaluated at each cross-section to determine the femoral cortical bone area. This study focused on five osteotomy lengths (2.5, 3, 3.5, 4, and 4.5 cm). The overlapped area between the proximal and distal cortical bone segments was defined as the contact area (S, mm2), and the contact area to distal cortical bone area ratio was defined as the coincidence rate (R). Three indicators were used to evaluate the matching and fitting of the osteotomy sites with the implanted Wagner cone stems: (1) higher S and R between the proximal and distal segments; (2) the effective fixation length of the femoral stem at the distal segments being at least 1.5 cm; and (3) osteotomy did not involve the isthmus. RESULTS: In all groups, S significantly decreased in the two proximal levels above the 0.5 cm level below the lesser trochanter (LT) compared with those below this level. In comparison, at osteotomy lengths from 2.5 to 4 cm, R significantly decreased in the three proximal levels. The optimal osteotomy levels ranged from 1.5 and 2.5 cm below the LT for an appropriately sized stem. CONCLUSIONS: Subtrochanteric osteotomy at the optimal level not only ensures fitting of the femur-femoral stem but also meets the requirements of a higher S and R to ensure adequate reduction and stabilization at the osteotomy site, which may contribute to the bone union. Although the optimal osteotomy level varies with the size of the femoral stem and the length of the subtrochanteric osteotomy, the optimal osteotomy levels for an appropriately sized Wagner cone femoral stem implantation range from 1.5 to 2.5 cm below the LT.

[Propensity score-matched study of uni-condylar arthroplasty in elderly patients with knee osteoarthritis].

OBJECTIVE: To investigate the clinical efficacy of unicompartmental knee arthroplasty (UKA) in the treatment of knee osteoarthritis in patients over 75 years old. METHODS: The clinical efficacy of primary fixed platform UKA in patients with osteoarthritis, was retrospectively analyzed from October 2014 to November 2020. Age, body mass index (BMI), range of motion (ROM), preoperative joint function score, the quality of life score and other preoperative indicators were measured by propensity score matching (PSM). The patients were divided into elderly group (≥75 years old) and control group (<75 years old). Oxford knee score(OKS), Western Ontario McMaster Universities osteoarthritis index(WOMAC), Short Form-12 including physical component summary (PCS), mental component summary(MCS), minimal clinically important difference(MCID ) and clinical complications were evaluated preoperatively and postoperatively. RESULTS: A total of 514 patients were analyzed, 428 patients fulfilled the inclusion criteria. A propensity-score matching study was conducted to eliminate confounding factors. After 1∶2 propensity match, there were 84 patients in elderly group (≥75 years), age ranged from 75 to 88 years old, with an average of (78.79±3.08) years old, and 168 patients in control group (<75 years), age ranged from 47 to 74 years old, with an average of (64.10±5.96)years old. The follow-up duration of two groups ranged from 12 to 84 months with an average of (29.35±16.52) months in elderly group, and 12 to 85 months with an average of (31.83±17.34) months in control group. There was only significant difference in age between the elderly and control groups preoperatively (P<0.01). Postoperatively, the elderly group showed significantly higher WOMAC (P<0.01) and lower SF-12 PCS scores (P<0.01) as compared to the control group. There was no significant difference between the elderly group and the control group in knee range of motion, OKS and the proportion of each scoring system reaching the minimum clinical difference value (P>0.05). In the aspect of preperative complications, the elderly group exhibited more surgical site complications and postoperative delirium compared to control group(P<0.05). The differences in other indicators including deep vein thrombosis, acute urinary retention, cardiovascular events, cerebrovascular events and radiolucent lines around prothesis were not statistically significant(P>0.05). CONCLUSION: UKA in the treatment of elderly patients over 75 years old with knee osteoarthritis was safe and feasible, and could obtain satisfactory short-term efficacy.

[Effect of open wedge tibial high osteotomy on patella position and joint function].

OBJECTIVE: To investigate the effect of open wedge tibial high osteotomy on patella position, anterior knee pain and joint function. METHODS: From June 2016 to June 2021, 109 patients (111 knees) with medial knee osteoarthropathy treated by open wedge tibial high osteotomy were included according to the inclusion and exclusion criteria, including 41 males and 68 females;the age ranged from 38 to 78 years old with an average of(57.98±7.07) years;the course of disease ranged from 1 to 36 months with an average of (8.58±6.91) months. The femoral tibial angle(FTA), medial proximal tibial angle(MPTA), weight bearing line(WBL) percentage, Caton Deschamps index (CD index), lateral patella tilt angle (LPTA) and lateral patella shift (LPS) were observed and compared before and after operation. Lysholm score was used to evaluate the knee function, visual analogue scale(VAS) was used to evaluate the degree of anterior knee pain, and Kellgren Lawrence(K-L) grading system was used to evaluate the progress of patellofemoral osteoarthritis. RESULTS: All patients were followed up for 6 to 38 months with an average of (12.41±2.40) months. The preoperative FTA, MPTA, WBL percentage, CD index, and LPTA were significantly different from those at the last follow-up(P<0.05). There was no significant difference between before and after LPS operation(P=0.78). Lysholm score increased from (58.79±7.90) scores to (76.05±7.36) scores (P<0.05). The VAS of anterior knee pain decreased from (3.28±1.95) scores to(1.07±1.75) scores(P<0.05). Knee patellofemoral osteoarthritis showed progressive changes, but there was no significant difference in K-L grading before and after operation (P>0.05). CONCLUSION: After open wedge tibial high osteotomy, the position of patella is lowered and the patella is tilted outward, but the knee function and anterior knee pain are significantly improved. Adverse changes in patella position caused by open wedge tibial high osteotomy may not affect clinical outcomes.

Mid-Term Outcomes of Cemented Stem and Subtrochanteric Shortening Derotational Osteotomy in Total Hip Arthroplasty for Crowe IV Developmental Dysplasia.

OBJECTIVE: Performing subtrochanteric osteotomy with cemented components in patients with Crowe IV developmental dysplasia of the hip (DDH) is technically challenging and not widely reported. This study aimed to evaluate the mid-term outcomes of cemented stem total hip arthroplasty (THA) with subtrochanteric femoral shortening and transverse derotational osteotomy in patients with Crowe IV DDH. METHODS: Data collected from patients with Crowe IV DDH who underwent cemented stem THA with subtrochanteric femoral shortening and transverse derotational osteotomy between 2010 and 2018 were retrospectively evaluated. The cemented Lubinus SP II femoral component and the cementless CombiCup acetabular component were used together in all cases. These data, including Harris hip scores, limb length discrepancy (LLD), severity of limp, Trendelenburg test, bone union, length of the resected femur, limb lengthening, level of the osteotomy site, and length bridging the osteotomy site, as well as complications, were analyzed. A paired Student t-test was used to analyze continuous variables, categorical data were compared using Fisher's exact probability test, and correlation analysis was performed using Spearman's rank correlation coefficient. RESULTS: Among 14 included patients (10 females and four males), the mean age was 60.4 years (range, 47-73). The mean follow-up period was 49.1 months, and no patient was lost to follow-up. The mean Harris hip score improved from 40.7 to 87.7. The mean LLD decreased from 52 to 12.7 mm. The mean length of the excised femoral segment was 38.4 mm, and the mean length of limb lengthening was 27.1 mm. The mean distance between the osteotomy site and the lesser trochanter was 21.1 mm after surgery. The mean length of the femoral stem bridging the osteotomy site was 97.6 mm. Finally, the mean osteotomy union time was 10.6 months. No statistically significant correlation was found between the osteotomy union time and these factors. No neurological deficits were noted. Delayed union was observed in one patient, and postoperative dislocation was observed in two patients. Cement leakage into the osteotomy gap was observed in one patient, however, no revisions were required, and no signs of loosening or migration were observed. CONCLUSIONS: Cemented stem THA combined with subtrochanteric femoral shortening and transverse derotational osteotomy is safe and effective in treating patients with Crowe IV DDH. Rather than leading to nonunion, cement leakage may negatively affect bone healing.

Pseudotumor and delayed recurrent dislocation after total hip arthroplasty with a modular femoral neck: A case report.

RATIONALE: Pseudotumor formation after hip arthroplasty is a rare complication that can occur not only at the head-neck junction but also at the modular neck-stem junction. Dislocation is a challenging and common complication of primary and revision total hip arthroplasty compared with other complications. Similarly, the association between pseudotumors and delayed recurrent dislocation remains unclear. PATIENT CONCERNS: We report the case of a 73-year-old woman with pseudotumor formation after total hip arthroplasty combined with a modular femoral neck. A delayed recurrent dislocation occurred in this case. Approximately 4weeks after the first revision surgery, redislocation occurred. DIAGNOSIS: The patient was eventually diagnosed with delayed recurrent artificial hip dislocation combined with a periprosthetic pseudotumor of the right hip. INTERVENTIONS: During the first revision surgery, a thickened, indurated cyst measuring 8×3×8cm with a red-brown wall containing brown fluid was completely excised. A cemented stem, combined with a BIOLOX Forte ceramic head, was implanted. Approximately 4weeks after surgery, redislocation occurred, and we cemented an elevated rim liner on the acetabular component with a metal head. OUTCOMES: At the last follow-up, 49 months after revision surgery, the patient was asymptomatic with a Harris hip score of 90. The patient had a satisfactory prognosis after treatment. LESSONS: The application of the modular-neck stem should be cautiously performed, particularly for modular prostheses containing different alloys. Pseudotumors and insufficient soft-tissue tension both contribute to hip instability, which may eventually lead to delayed repeated dislocation. In addition, femoral offset must be considered. Cement-liner technology may be used for aging patients who are less active. This case report, focusing on pseudotumors and delayed recurrent dislocations, aimed to identify factors that may support this diagnosis, which is easy to miss. Consequently, it can provide further details on the treatment process and alert orthopedic surgeons to this infrequent but important cause of delayed recurrent dislocation.

Arthroscopic all-inside repair with suture hook for horizontal tear of the lateral meniscus at the popliteal hiatus region: a preliminary report.

BACKGROUND: Arthroscopic surgery procedures vary depending on the types of meniscus tear, including meniscectomy and meniscus repair. Among the several types of meniscus tear, the horizontal tear of the lateral meniscus at the popliteal hiatus region is a common injury, and its surgical treatment is still inconsistent. METHODS: Between January 2018 and October 2018, 20 patients who underwent all-inside repair with suture hook for the horizontal tear of the lateral meniscus at the popliteal hiatus region were recruited. Any operative complication was recorded, and postoperative MRI scans were conducted at the 6 months. The clinical results were graded based on the scale of the Lysholm knee score preoperatively and at follow-up. RESULTS: No operative complications were recorded. Postoperative MRIs at the 6 months showed that there was no re-tear for all patients, though signal intensity remained high in T2-weighted MRI in the lateral meniscus for nine cases. The average preoperative Lysholm knee score was 58.6 ± 10.1, which increased significantly to 89.3 ± 7.8 (t = - 11.01, p = 0.001) at the last follow-up. Recurrence or aggravation of symptoms was not noted at the final follow-up. CONCLUSION: All-inside repair with suture hook may be a good option for the horizontal tear of the lateral meniscus at the popliteal hiatus region which preserves the meniscus; avoids iatrogenic injury on the adjacent popliteal tendon, common peroneal nerve, and inferior lateral geniculate artery.

[Fixed-bearing unicompartmental knee arthroplasty for medial compartmental knee osteoarthritis].

OBJECTIVE: To evaluate short-term clinical results of fixed-bearing unicompartmental knee arthroplasty (UKA) for patients with medial compartmental knee osteoarthritis. METHODS: From January 2015 to December 2017, 62 patients with medial compartmental knee osteoarthritis were treated by fixed-bearing UKA. Among them, including 19 males and 43 females, aged from 47 to 83 years old with an average of (65.3±8.2) years old. The courses of disease ranged from 5 to 72 months with an average of(19.4±14.3) months. Postoperative complications were observed, VAS score was used to observe degree of pain relief, Hospital for Special Surgery(HSS) score was used to evaluate clinical effects. RESULTS: All patients were followed up from 4 to 40 months with an average of(19.9 ±10.2) months. The incision healed well without blood transfusion, hospital stays ranged from 2 to 10 days with an average of (3.5±1.6) days. No deep infection, dislocation, loosing or per prosthetic fracture occurred after operation, while 1 patient suffered from posterior tibial vein thrombosis. HSS score improved from 69.9±7.2 before operation to 90.1±7.4 at final following-up, and 51 patients obtained excellent results, 9 patients good and 2 moderate. VAS score decreased from 3.8±0.9 before operation to 1.1±0.9 at final following-up. CONCLUSIONS: Fixed-bearing UKA for medial compartmental knee osteoarthritis could obtain short-term clinical results for shorter hospital stay, less complications. with fewer complication and fast recovery.

[Clinical outcome of enhanced recovery after surgery for hemiarthroplasty for the treatment of femoral neck fractures in elderly patients].

OBJECTIVE: To analyze and evaluate the clinical outcomes of enhanced recovery after surgery(ERAS) for hemiarthroplasty for the treatment of femoral neck fractures in elderly patients. METHODS: From January 2015 to December 2016, 466 patients with femoral neck fractures were admitted in our department. Among them, 154 patients were more than 80 years old, with an average age of (83.9±3.2) years old (ranged, 80 to 96 years old), including 27 males and 127 females. According to Garden classification system, 68 cases were type III and others were type IV. ERAS for hemiarthroplasty were performed for all the patients. The time before operation, blood transfusion rate, complications rate, lenth of stay and Harris score system were evaluated. RESULTS: Among 154 patients, 142 patients were followed up, with an average duration of 24.6 months(ranged, 14 to 38 months). Thirty-two patients (20.8%) completed the operation within 48 hours after admission, 67 patients(43.5%) completed the operation within 72 hours after admission, 76 patients(49.4%) discharged within 48 hours after operation, and the blood transfusion rate was 15.9%. One patient was re-hospitalized because of prosthetic dislocation. The re-hospitalization rate was 0.6%. No other patients were re-hospitalized because of superficial or deep infection or periprosthetic fracture. At the latest follow-up, the Harris hip score was 90.2±7.1, 106 patients got an excellent result, 23 good and 9 fair. CONCLUSIONS: ERAS for hemiarthroplasty can effectively shorten hospitalization time, relieve pain, reduce blood transfusion rate, reduce postoperative complications, and do not increase the readmission rate of elderly patients with femoral neck fracture, which can achieve good clinical efficacy.

Biomechanical Analysis of a Novel Intercalary Prosthesis for Humeral Diaphyseal Segmental Defect Reconstruction.

OBJECTIVE: To study the biomechanical properties of a novel modular intercalary prosthesis for humeral diaphyseal segmental defect reconstruction, to establish valid finite element humerus and prosthesis models, and to analyze the biomechanical differences in modular intercalary prostheses with or without plate fixation. METHODS: Three groups were set up to compare the performance of the prosthesis: intact humerus, humerus-prosthesis and humerus-prosthesis-plate. The models of the three groups were transferred to finite element software. Boundary conditions, material properties, and mesh generation were set up for both the prosthesis and the humerus. In addition, 100 N or 2 N.m torsion was loaded to the elbow joint surface with the glenohumeral joint surface fixed. Humeral finite element models were established according to CT scans of the cadaveric bone; reverse engineering software Geomagic was used in this procedure. Components of prosthetic models were established using 3-D modeling software Solidworks. To verify the finite element models, the in vitro tests were simulated using a mechanical testing machine (Bionix; MTS Systems Corporation, USA). Starting with a 50 N preload, the specimen was subjected to 5 times tensile (300 N) and torsional (5 N.m) strength; interval time was 30 min to allow full recovery for the next specimen load. Axial tensile and torsional loads were applied to the elbow joint surface to simulate lifting heavy objects or twisting something, with the glenohumeral joint surface fixed. RESULTS: Stress distribution on the humerus did not change its tendency notably after reconstruction by intercalary prosthesis whether with or without a plate. The special design which included a plate and prosthesis effectively diminished stress on the stem where aseptic loosening often takes place. Stress distribution major concentrate upon two stems without plate addition, maximum stress on proximal and distal stem respectively diminish 27.37% and 13.23% under tension, 10.66% and 11.16% under torsion after plate allied. CONCLUSION: The novel intercalary prosthesis has excellent ability to reconstruct humeral diaphyseal defects. The accessory fixation system, which included a plate and prosthesis, improved the rigidity of anti-tension and anti-torsion, and diminished the risk of prosthetic loosening and dislocation. A finite element analysis is a kind of convenient and practicable method to be used as the confirmation of experimental biomechanics study.

[Evaluation of early clinical results of two stage hip replacement after failed internal fixation for femoral neck fractures].

OBJECTIVE: To evaluate the early clinical results of two stage hip replacement after failed internal fixation for femoral neck fractures in young patients. METHODS: From June 2008 to June 2010,24 patients with femoral head necrosis caused by failed internal fixation were treated with hip arthroplasty. Among them, 12 patients were male and 12 patients were female, with an average age of 42.9 years old (ranged, 18 to 58). According to Harris score and X-ray examination, the clinical result was evaluated. RESULTS: Twenty-three cases were followed up with an average age of 34.4 months (ranged, 25 to 48). After operation, 1 case complicated with the dislocation of hip joint. No deep infection of hip joint, prosthetic loosing or peripheral fracture was found. The mean Harris score was 90.9 +/- 4.3, and 18 obtained excellent results, 4 good and 1 fair. CONCLUSION: Although treatment of femoral head necrosis with two stage hip replacement after failed internal fixation is difficult during operation, its early result is satisfactory.

[Case-control study on acute colonic pseudo-obstruction after total hip or knee arthroplasty].

OBJECTIVE: To investigate the incidence, predisposing factors and therapeutic modalities of acute colonic pseudo-obstruction (ACPO) in patients after total hip arthroplasties (THA) and total knee arthroplasties (TKA). METHODS: From January 2006 to December 2009, 12 patients with ACPO after THA and TKA operation were investigated retrospectively,who were viewed as the ACPO group. There were 10 males and 2 females with an average age of (78 +/- 12) years in the ACPO group. Other 853 patients without ACPO after THA and TKA operation were viewed as the control group treated at the same period. The incidence of ACPO was calculated. The clinical data were collected and compared between the two groups including patient age, gender, procedure, anesthetic class, clinical presentation, radiographic findings, duration from index surgery to diagnosis of ACPO, treatment, postoperative mobilization time, and length of hospital stay. RESULTS: The incidence of ACPO was 1.4%. The incidence of primary THA (1.3%) was higher than that of primary TKA (0.4%); the incidence of hip and knee revisions (5.0%) was higher than that of primary THA and TKA (1.0%); there was no difference in incidence between hip revisions (5.5%) and knee revisions (4.0%). The mean age was (78 +/- 12) years old in ACPO group and (71 +/- 13) in the control group. The male/female ratio was 5:1 in ACPO group and 2:3 in control group. There were statistical differences in mean age and gender ratio between the two groups. No association was found with respect to anesthetic class. On average, ACPO occurred at 2.5 days after index surgery. The abdominal distention occurred in all 12 cases, nausea or vomiting in 8 cases and abdominal pain in 3 cases. Radiographically cecal dilation occurred in all cases and intestinal dilation in 3 cases. All patients initially were treated conservatively with immediate cessation of oral intake,a nasogastric tube and oral mineral oil. Three patients received a rectal tube. Only 1 patient required endoscopic decompression. There were no deaths after ACPO in the series. Mean mobilization time after surgery averaged (5.0 +/- 2.2) days in ACPO group compared with (2.5 +/- 1.1) days in the control group. Mean hospital stay averaged (16.5 +/- 6.4) days in ACPO group compared with (10.5 +/- 4.5) days in the control group. There were statistical differences in mean mobilization time after surgery and mean hospital stay between two groups. CONCLUSION: ACPO mainly happened in old male patients. The majority cases response to conservative treatment and their prognoses are good. But ACPO will delay mobilization time after surgery and increase hospital stay.

[Short-term result of hip resurfacing arthroplasty in the treatment of patients with femoral head necrosis].

OBJECTIVE: To study short-term results of hip resurfacing arthroplasty (HRA) in the treatment of patients with avascular necrosis of femoral head (ANFH), and to explore indication and strategy in this surgery. METHODS: From December 2006 to December 2009, 37 patients (43 hips) with avascular necrosis of femoral head were treated with total hip resurfacing arthroplasty. Among the patients, 25 patients were male and 12 patients were female, with an average age of 44.5 years (ranged, 21 to 67 years). According to ARCO classification, 3 hips were 3A stage, 6 hips were 3B stage, 16 hips were 3C stage and 18 hips were 4 stage. X-ray evaluation of the patients were conducted. The clinical results were evaluated by the Harris hip score system including pain,range of motion, correction of deformity and total function. RESULTS: Thirty-four patients (40 hips) were followed up with an average period of 32.4 months (ranged, 16 to 53 months), and 3 patients were lost. Thirty-seven hips got complete relief of joint pain and 3 patients feel aching pain after walking. There was 1 heterotopic ossification, no femoral neck fracture no dislocation, no infection and no revision in all patients. From pre-operation to present, the average Harris hip score improved significantly from (51.5 +/- 1.7) to (94.3 +/- 1.4). Thirty-seven hips got an excellent result, 3 hips good and no poor. CONCLUSION: The total hip resurfacing arthroplasty is an effective solution for the problems of the younger and active patients with ANFH, and the short-term results are satisfying.

[Comparison of humeral head replacement and internal fixation for the treatment of 3 parts and 4 parts fractures of proximal humerus in the elderly].

OBJECTIVES: To compare the indication, technical keys during surgery and early results of humeral head replacement and internal fixation for the 3 parts and 4 parts fractures of proximal humerus in the elderly. METHODS: From July. 2004 to July. 2006,58 patients with 3 parts and 4 parts fractures of proximal humerus were randomly treated with AO locked compressive plates (LCP) or humeral head replacement. In LCP group, there were 12 males and 16 females with an average age of (66.5 +/- 1.4) years, including 24 cases of 3 parts fractures, 1 case of 3 parts fractures with dislocation, 2 cases of 4 parts fractures and 1 case of 4 parts fractures with dislocation. In the humeral head replacement group,there were 12 males and 18 females with an average age of (68.9 +/- 3.5) years, including 9 cases of 3 parts fractures, 2 cases of 3 parts fractures with dislocation, 12 cases of 4 parts fractures, 4 cases of 4 parts fractures with dislocation and 3 cases of humeral head split fractures. Trauma series X-rays of shoulder were taken after operation, 2-week, 6-week, 10-week, 16-week, 6-month and the latest followed-up. VAS, SST (simple shoulder test) questionnaire, ASES (American shoulder & elbow surgeon)score, Constant-Murley score and UCLA score had been adopted for evaluation at the latest followed-up. RESULTS: The mean followed-up period of LCP group was 29.8 months and that of humeral head replacement group was 28.2 months. VAS of LCP group and humeral head replacement group were (2.2 +/- 1.5) and (2.6 +/- 1.9), respectively. There was a statisticaly difference between the two groups (P = 0.002). The degrees of forward elevation of shoulder in LCP group and humeral head replacement group were 110.2 degrees (81 degrees to 130 degrees) and 120.2 degrees (89 degrees to 140 degrees), respectively. There was a statistical difference between the two groups (P = 0.031). ASES score, Constant-Murley score, UCLA score and response "yes" in SST questionnaire in LCP group were 87.7 +/- 2.2, 83.9 +/- 6.8, 30.3 +/- 2.2, 8.0 +/- 0.9, and in humeral head replacement group were 86.4 +/- 4.5, 85.5 +/- 5.6, 31.2 +/- 2.1, 9.0 +/- 0.7, respectively. There was no significant difference between the two groups in ASES score, Constant-Murley score, UCLA score and SST questionnaire. CONCLUSION: Both humeral head replacement and internal fixation are effective treatment for the 3 parts and 4 parts fracture of proximal humerus in the elderly. Humeral head replacement is more technically demanding and has a strict indications. The satisfactory results of humeral head replacement are based on the suitable placement of prostheses and the correct reconstruction of rotator cuff insertion.

[Hip resurfacing arthroplasty in patients with ankylosing spondylitis].

OBJECTIVE: To study the short-term results of metal on metal hip resurfacing arthroplasty (HRA) for the treatment of patients with ankylosing spondylitis (AS), to explore the indications and technology of this surgery. METHODS: From February 2006 to April 2008, 11 patients (15 hips) with ankylosing spondylitis were treated with metal on metal total hip resurfacing arthroplasty. Among them, 9 patients were male, and 2 patients were female, with an average age of 32.5 years (ranged from 16 to 53 years). The comparative study on preoperative and postoperative pain, range of motion, correction of deformity and function evaluation were performed. The preoperative and postoperative Harris scores were compared and the feasibility and technical difficulty were analyzed. RESULTS: Ten patients were followed up for an average period of 16.2 months (ranged from 8 to 34 months) and 1 patient was lost. Pain disappeared in 10 patients. There were no heterotopic ossification, no femoral neck fracture, no dislocation, no infection and no revision in all patients. From preoperation to present, the mean flexion angle of hip was improved from preoperative 0 degrees to 75 degrees to postoperative 35 degrees to 105 degrees; the mean abducting angle of hip was improved from preoperative 0 degrees to 30 degrees to postoperative 15 degrees to 55 degrees; and the average Harris hip score improved significantly from (30.9 +/- 3.4) (2-47) to (85.1 +/- 3.1) (46-94). According to evaluation criteria, 10 hips got an excellent result, 3 good and 1 poor. CONCLUSION: The total hip resurfacing arthroplasty is an effective solution for the treatment of the younger and active patients with AS and it shows satisfactory short-term results. It is very significant to analysis the different conditions of patients so as to choose proper strategy.