Ranitidine Use and Incident Cancer in a Multinational Cohort.

Importance: Ranitidine, the most widely used histamine-2 receptor antagonist (H2RA), was withdrawn because of N-nitrosodimethylamine impurity in 2020. Given the worldwide exposure to this drug, the potential risk of cancer development associated with the intake of known carcinogens is an important epidemiological concern. Objective: To examine the comparative risk of cancer associated with the use of ranitidine vs other H2RAs. Design, Setting, and Participants: This new-user active comparator international network cohort study was conducted using 3 health claims and 9 electronic health record databases from the US, the United Kingdom, Germany, Spain, France, South Korea, and Taiwan. Large-scale propensity score (PS) matching was used to minimize confounding of the observed covariates with negative control outcomes. Empirical calibration was performed to account for unobserved confounding. All databases were mapped to a common data model. Database-specific estimates were combined using random-effects meta-analysis. Participants included individuals aged at least 20 years with no history of cancer who used H2RAs for more than 30 days from January 1986 to December 2020, with a 1-year washout period. Data were analyzed from April to September 2021. Exposure: The main exposure was use of ranitidine vs other H2RAs (famotidine, lafutidine, nizatidine, and roxatidine). Main Outcomes and Measures: The primary outcome was incidence of any cancer, except nonmelanoma skin cancer. Secondary outcomes included all cancer except thyroid cancer, 16 cancer subtypes, and all-cause mortality. Results: Among 1 183 999 individuals in 11 databases, 909 168 individuals (mean age, 56.1 years; 507 316 [55.8%] women) were identified as new users of ranitidine, and 274 831 individuals (mean age, 58.0 years; 145 935 [53.1%] women) were identified as new users of other H2RAs. Crude incidence rates of cancer were 14.30 events per 1000 person-years (PYs) in ranitidine users and 15.03 events per 1000 PYs among other H2RA users. After PS matching, cancer risk was similar in ranitidine compared with other H2RA users (incidence, 15.92 events per 1000 PYs vs 15.65 events per 1000 PYs; calibrated meta-analytic hazard ratio, 1.04; 95% CI, 0.97-1.12). No significant associations were found between ranitidine use and any secondary outcomes after calibration. Conclusions and Relevance: In this cohort study, ranitidine use was not associated with an increased risk of cancer compared with the use of other H2RAs. Further research is needed on the long-term association of ranitidine with cancer development.

Dual mobility articulation total hip arthroplasty for displaced neck fracture in elderly with neuromuscular disorder.

PURPOSE: Neuromuscular disease is well known to be at increased risk of complications following hip replacement surgeries. This study is prospectively conducted to investigate clinical performance and survivorship of total hip arthroplasty (THA) using dual mobility articulation in femoral neck fractures of elderly with neuromuscular disease. MATERIALS AND METHODS: We prospectively enrolled 162 patients (162 hips) with displaced femoral neck fracture who gave informed consent for dual mobility articulation THA. Of the 162 patients, 35 patients had neuromuscular disease including cerebral palsy, poliomyelitis, hemiplegia, and Parkinson disease (NM group). The other 127 patients had no history of neuromuscular disease (non-NM group). The mean age was 76.5 years (range, 60 - 95) and female ratio was 71.0% (115/162). Clinical outcomes including Harris hip score (HHS), University of California Los Angles activity (UCLA) score were compared between the two groups. Computed tomography and serial radiographs were obtained after surgery. Postoperative complications and reoperation including revision were recorded. RESULTS: Pain-VAS and all clinical scores of the NM group were comparable to those of the non-NM group. The incidence of dislocation in the NM group did not differ from that in Non-NM group (2/35, 5.7% versus 5/127, 3.9%, p = 0.645). Reoperation was performed in 3 hips (3/35, 8.6%) of the NM group and in 4 hips (4/127, 3.1%) of the non-NM group (p = 0.173). Kaplan-Meier survivorship with an end point of revision for any reason was 97.1% (95% confidence interval [CI], 0.92 to 1.03) in the NM group and 98.4% (95% CI, 0.96 to 1.01) in the non-NM group at 7.3 years after surgery. CONCLUSIONS: In elderly with neuromuscular disease, THA with dual mobility articulation is a reasonable option as a treatment for femoral neck fractures.

Comparative safety and effectiveness of alendronate versus raloxifene in women with osteoporosis.

Alendronate and raloxifene are among the most popular anti-osteoporosis medications. However, there is a lack of head-to-head comparative effectiveness studies comparing the two treatments. We conducted a retrospective large-scale multicenter study encompassing over 300 million patients across nine databases encoded in the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM). The primary outcome was the incidence of osteoporotic hip fracture, while secondary outcomes were vertebral fracture, atypical femoral fracture (AFF), osteonecrosis of the jaw (ONJ), and esophageal cancer. We used propensity score trimming and stratification based on an expansive propensity score model with all pre-treatment patient characteritistcs. We accounted for unmeasured confounding using negative control outcomes to estimate and adjust for residual systematic bias in each data source. We identified 283,586 alendronate patients and 40,463 raloxifene patients. There were 7.48 hip fracture, 8.18 vertebral fracture, 1.14 AFF, 0.21 esophageal cancer and 0.09 ONJ events per 1,000 person-years in the alendronate cohort and 6.62, 7.36, 0.69, 0.22 and 0.06 events per 1,000 person-years, respectively, in the raloxifene cohort. Alendronate and raloxifene have a similar hip fracture risk (hazard ratio [HR] 1.03, 95% confidence interval [CI] 0.94-1.13), but alendronate users are more likely to have vertebral fractures (HR 1.07, 95% CI 1.01-1.14). Alendronate has higher risk for AFF (HR 1.51, 95% CI 1.23-1.84) but similar risk for esophageal cancer (HR 0.95, 95% CI 0.53-1.70), and ONJ (HR 1.62, 95% CI 0.78-3.34). We demonstrated substantial control of measured confounding by propensity score adjustment, and minimal residual systematic bias through negative control experiments, lending credibility to our effect estimates. Raloxifene is as effective as alendronate and may remain an option in the prevention of osteoporotic fracture.

Acetabular revision arthroplasty using press-fitted jumbo cups: an average 10-year follow-up study.

INTRODUCTION: Acetabular revision arthroplasty using jumbo cups for moderate-to-severe acetabular defects has varied outcomes. We evaluated the clinical and radiological outcomes of acetabular revision arthroplasty using a press-fitted jumbo cup and sought to identify factors that influence outcomes during intermediate follow-up. MATERIALS AND METHODS: Eighty patients (47 men, 33 women; 80 hips) who underwent acetabular revision arthroplasty using press-fitted jumbo cups were included. The mean follow-up period was 10.4 years. Harris hip score (HHS), presence of groin pain, radiographic results, and Kaplan-Meier survival curves were evaluated. Implant design and surgery-related and patient-related factors were assessed to identify influential factors for cup loosening. Migration and wear analyses were performed using Einzel-Bild-Röntgen-Analyse software. RESULTS: The mean preoperative HHS of 53 had improved to 77 at the final follow-up (p = 0.005). Nine patients experienced groin pain. Acetabular cup loosening was observed in seven cups (8.7%), and one jumbo cup was replaced with a reinforcement cage. The survival rate of the acetabular cup was 91% at 16 years according to the Kaplan-Meier analysis. Osteolysis was identified around the cup in six cases (7.5%). Acetabular cup loosening occurred more frequently in patients with conventional polyethylene liners than in those with highly cross-linked polyethylene liners (p = 0.045). The mean total migration was 1.52 mm, and the mean total wear was 0.98 mm. There was a positive correlation between total migration and total wear (p = 0.023; Spearman's rho = 0.388). The mean wear rate of the patients with the cup inclination angle < 50° was significantly lower than those with the cup inclination angle > 50° (p = 0.001). There were four cases of complications (three dislocations and one infection) that did not require revision surgery. CONCLUSION: Press-fitted jumbo cups for acetabular revision arthroplasty exhibited encouraging results during follow-up for an average of 10 years. Use of highly cross-linked polyethylene liners and proper placement of the acetabular component with an inclination angle < 50° may contribute to better clinical outcomes after acetabular revision arthroplasty with jumbo cups.

Three-dimensional analysis of acetabular orientation using a semi-automated algorithm.

Understanding the morphology of the acetabulum is necessary for preoperative evaluation in hip surgery. The purpose of this study was to (1) establish a novel method for measuring three-dimensional (3D) acetabular orientation, (2) quantify the reliability of this method, and (3) describe relevant characteristics of three-dimensional (3D) acetabular orientation among normal Asian subjects. Computed tomography (CT) scans of the pelvis that had been performed for suspected non-musculoskeletal conditions were obtained from 200 subjects (60 males, 140 females). A novel method was developed to measure 3D acetabular orientation with a semi-automatically determined pelvic coordinate system based on the anterior pelvic plane (APP). To quantify the robustness of our method, we analyzed the results obtained from 20 patients at different times and with different raters and pelvic poses in the same CT volume. To determine morphological differences of the acetabulum by age and sex, we analyzed the parameters of 200 CT volumes. Each intraclass correlation coefficient (ICC) values for intra- and inter-observer reliability were over 0.975 and 0.945, demonstrating high reliability. Furthermore, agreement between the angles determined from the original volume and the rotated volume was nearly perfect (ICCs > 0.956). Multiple linear regression analysis with age and sex as covariates indicated that acetabular inclination was not significantly associated with age (p = 0.687) or sex (p = 0.09). There was also no evidence that acetabular anteversion was associated with age (p = 0.383) or sex (p = 0.53). Our method showed excellent reliability for determining acetabular orientation, as it is robust, fast, and easily applicable to larger populations. In addition, the results of the analysis of acetabular orientation by age and sex can be used as a reference in various diagnostic procedures in orthopedics.

Long-Term Outcomes After Metal-on-Metal Total Hip Arthroplasty With a 28-mm Head: A 17- to 23-Year Follow-Up Study of a Previous Report.

BACKGROUND: Second-generation, metal-on-metal total hip arthroplasty (MoM THA) using a 28-mm head has shown favorable results compared with large head MoM THA. The purpose of this study is to evaluate the long-term outcomes of cementless primary MoM THA with a 28-mm head and the incidence of osteolysis using computed tomography. METHODS: A total of 92 patients (53 men and 39 women) who underwent primary cementless MoM THA (114 hips) with a 28-mm head were enrolled in this study. Their mean age was 46.2 years at the time of surgery. The mean follow-up duration was 20 years. The Harris hip score, presence of thigh or groin pain, radiographic results, presence of peri-implant osteolysis, histologic analysis, and Kaplan-Meier survival curves were evaluated. RESULTS: The mean preoperative Harris hip score of 50.5 improved to 85.1 at the final follow-up. Eight patients (8 hips) experienced groin pain, but none had thigh pain. Twelve revisions (6.2%) were performed including 10 hips for aseptic loosening with osteolysis and 2 hips for periprosthetic fracture around the stem. At 23 years, 91% of patients were free from revision of the acetabular component due to aseptic loosening and 90.1% were free from revision of both femoral and acetabular components due to any reason. Osteolysis was identified around the cup in 12 cases (10.5%) and around the stem in 7 cases (6.1%). CONCLUSION: MoM THA with a 28-mm head showed a relatively low rate of aseptic implant loosening at a mean follow-up of 20 years.

The incidence of hip dislocation and suture failure according to two different types of posterior soft tissue repair techniques in total hip arthroplasty: a prospective randomized controlled trial.

PURPOSE: Although the posterolateral approach for hip arthroplasty is popular and has numerous advantages, it has been known to have a propensity for dislocation. The repair of short external rotator muscles with capsule is important for reducing dislocation. The purpose of this study is to investigate the incidence of suture failure, dislocation, and time to failure for two repair techniques for posterior soft tissue repair during total hip arthroplasty. METHODS: In this study of 167 total hip arthroplasties in 159 patients, we reattached the short external rotator tendon with posterior capsule to the greater trochanter transosseously (tendon-to-bone, 87 hips) or the gluteus medius tendon (tendon-to-tendon, 80 hips). Radiopaque markers were attached to each suture side < 1.2 cm apart. The distance between the markers was radiographically measured at variable time points postoperatively. Failure was defined by a distance between markers of ≥ 2.5 cm or marker invisibility. The mean follow-up period was 28.8 (12-45) months. RESULTS: Suture failure was observed less frequently in the tendon-to-bone group (18.4%) than in the tendon-to-tendon group (65%; p < 0.001). Failure mostly occurred within two weeks post-operatively: 93.8% for tendon-to-bone repair (p < 0.001) and 90.4% for tendon-to-tendon repair (p = 0.025). The dislocation rate was significantly higher in the tendon-to-tendon group (7. vs 1.1%; p = 0.041). A significant correlation was observed between suture failure and dislocation (p = 0.013). CONCLUSIONS: Tendon-to-bone repair is superior to tendon-to-tendon repair based on lower suture failure and dislocation rates.

Dislocations after use of dual-mobility cups in cementless primary total hip arthroplasty: prospective multicentre series.

BACKGROUND: The purpose of this study was to investigate the incidence of dislocation and specific complications of the dual-mobility cup. METHODS: The arthroplasties involved 167 hips in 165 patients; 51 hips (30.5%) were in men and 116 (69.4%) were in women. The active articulation E1® dual-mobility cup (Biomet, Warsaw, IN, USA) was used, and the surgical approach was posterolateral in 120 hips and anterolateral in 47 hips. RESULTS: Four (2.3%) dislocations were observed. Mean time of dislocation was 30.5 days post-operatively. Three incomplete reductions occurred during closed reduction. When comparing parameters between dislocation and no-dislocation groups, there were no differences in patient and surgical parameters. However, all dislocations occurred in patients with femoral neck fractures and in the posterolateral approach group. CONCLUSION: The incidence of dislocation in total hip arthroplasty (THA) using a dual-mobility cup was acceptable, and cup diameter of the dislocation group was substantially larger than that of no-dislocation group. Based on clinical outcomes of our study, we conclude that the dual-mobility cup is a reliable option in THA, and further studies are necessary.

Management of Blood Loss in Hip Arthroplasty: Korean Hip Society Current Consensus.

The volume of hip arthroplasty is stiffly increasing because of excellent clinical outcomes, however it has not been shown to decrease the incidence of transfusions due to bleeding related to this surgery. This is an important consideration since there are concerns about the side effects and social costs of transfusions. First, anemia should be assessed at least 30 days before elective hip arthroplasty, and if the subject is diagnosed as having anemia, an additional examination of the cause of the anemia should be carried and steps taken to address the anemia. Available iron treatments for anemia take 7 to 10 days to facilitate erythropoiesis, and preoperative iron supplementation, either oral or intravenous, is recommended. When using oral supplements for iron storage, administer elemental iron 100 mg daily for 2 to 6 weeks before surgery, and calculate the dose using intravenous supplement. Tranexamic acid (TXA) is a synthetic derivative of the lysine component, which reduces blood loss by inhibiting fibrinolysis and clot degradation. TXA is known to be an effective agent for reducing postoperative bleeding and reducing the need for transfusions in primary and revision total hip arthroplasties. Patient blood management has improved the clinical outcome after hip arthroplasty through the introduction and research of various agents, thereby reducing the need for allogeneic blood transfusions and reducing the risk of transfusion-related infections and the duration of hospitalizations.

A robust method to extract the anterior pelvic plane from CT volume independent of pelvic pose.

PURPOSE: The anterior pelvic plane (APP) is commonly used as a reference plane to assess acetabular orientation. However, conventional methods for determining the APP may not be accurate and are prone to user variability. To overcome these issues, we developed a robust method to accurately extract the APP independent of pelvic pose using three-dimensional pelvic computed tomography (CT). MATERIALS AND METHODS: Twenty-eight studies for suspected nonmusculoskeletal conditions were obtained. The APP was determined by four landmarks that were automatically extracted from user-defined regions of interest (ROIs) with compensation of pelvic pose. The APP defined from these landmarks was quantitatively compared to the APPs determined by an expert and an unskilled. Intraobserver reliability was measured to evaluate the time-interval variability. Finally, we evaluate the robustness of this method to patient posture using an arbitrarily rotated volume. The intraclass correlation coefficients (ICCs) were calculated to determine the interobserver and intraobserver reliabilities. RESULTS: The ICC values for the four landmarks and the APP were similar between the semiautomated method and expert determination (ICC >0.937). The ICC values for intraobserver reliability over time for our method were all 1, demonstrating high reliability. Furthermore, agreement between the parameters determined from the original volume and the rotated volume was nearly perfect. CONCLUSIONS: Our method is a useful measurement tool for the APP as it is robust, and the results were similar to an experienced surgeon's determination. Furthermore, it was independent to the direction of the CT slice and more robust than a measurement by an unskilled.

Measurement of change on medial and lateral joint gaps by navigation system in multi-radius PS TKA.

BACKGROUND: The purpose of this study was to evaluate the joint gap kinematics in posterior-stabilized total knee arthroplasty (PS TKA). METHODS: Between January 2010 and April 2011, 44 consecutive patients (55 knees) who underwent primary PS TKA using the navigation system were assessed. There were 37 women and 7 men with a mean age at operation of 63 years (range; 58-73 years). After fixation of all components with cement and insertion of polyethylene trial insert, medial and lateral joint gap measurements were carried out without distraction force and separately using a navigation system on each flexion angles. The joint gaps were measured before and after deflation of tourniquet, first with patella everted and then reduced. RESULTS: Deflation of tourniquet did not effect on gap. In patellofemoral joint reduction situation, the medial gap relatively maintained throughout the range of knee motion, but the lateral gap is gradually decreasing with knee flexion from 30° to 120° flexion. However, in patellar eversion situation, the medial gap showed a significant increase and also statistically significantly increased compared with patellar reduced position over 90° knee flexion status, but the lateral gaps are decreased compared with patellofemoral reduction situation throughout the range of knee motion except full flexion status. In more physiologic status that is patella reduced and tourniquet deflated status, the average medial joint gap change was 2.30 ± 1.64 mm and the average lateral joint gap change was 2.90 ± 1.53 mm throughout the range of motion. CONCLUSIONS: Medial and lateral joint gaps showed different patterns with patellar eversion and patellofemoral joint reduction. However, such changes occurred within 3 mm in average throughout whole range of knee motion even with multi-radius femoral component.

Minimum effective local anesthetic volume for surgical anesthesia by subparaneural, ultrasound-guided popliteal sciatic nerve block: A prospective dose-finding study.

Because of its rapid onset time, recent years have seen an increase in the use of ultrasound (US)-guided popliteal sciatic nerve block (PSNB) via subparaneural injection for induction of surgical anesthesia. Moreover, in below-knee surgery, combined blocks, as opposed to sciatic nerve block alone, have become more common. These combined blocks often require a large volume of local anesthetic (LA), thus increasing the risk of local-anesthetic systemic toxicity (LAST). Thus, to decrease the risk of LAST, it is important to know the minimum effective volume (MEV) required for an adequate block. We, therefore, aimed to determine the MEV of ropivacaine 0.75% for induction of surgical anesthesia by the method of US-guided popliteal sciatic nerve block via subparaneural injection.Thirty patients underwent a US-guided PSNB with ropivacaine 0.75% at a 20-mL starting volume. Using a step-up/step-down method, we determined injection volumes for consecutive patients from the preceding patient's outcome. When an effective block was achieved within 40 minutes after injection, the next patient's volume was decreased by 2 mL. If the block failed, the next patient's volume was increased by 2 mL. The sensory and motor blockade was graded according to a 4-point scale. The block was considered a success if a combination of anesthesia and paresis (a score of 3 for both the sensory and motor nerves) was achieved within 40 minutes. The primary outcome measure was the MEV resulting in a successful subparaneural block of the sciatic nerve in 50% of patients (MEV50). Additionally, the data were processed with a probit regression analysis to determine the volume required to produce a complete sciatic nerve block in 90% of subjects (ED90).The MEV50 of 0.75% ropivacaine is 6.14 mL (95% confidence interval, 4.33-7.94 mL). The ED90 by probit analysis for a subparaneural injection was 8.9 mL (95% CI, 7.09-21.75 mL).The 6.14-mL MEV50 of ropivacaine 0.75% represents a 71% reduction in volume compared with neurostimulation techniques and a 14.7% reduction in volume compared with US-guided PSNB using the alternative perineural injection technique.

Isolated acetabular revision with ceramic-on-ceramic bearings using a ceramic head with a metal sleeve.

The purpose of this study is to evaluate results of isolated acetabular revision with ceramic-on-ceramic bearings using a ceramic head with a metal sleeve. A retrospective review of fifty-three hips was performed. The mean patient age was 49.9years and the mean follow-up period was 5.7years. The mean modified Harris hip score improved from 47.5, pre-operatively, to 84.7 at the time of last follow-up (P<0.001). Two patients reported squeaking of the hip. Three patients experienced loosening cup, necessitating re-revision surgery. There was a significant difference of acetabular bone defect between loose cup group and stable cup group (P=0.018). There were no ceramic fractures and no osteolysis. The survival rate of the acetabular cup at the mid-term follow-up was 94.3%. In conclusion, ceramic head with a metal sleeve can be a reliable option for isolated acetabular revision.

Is second generation metal-on-metal primary total hip arthroplasty with a 28 mm head a worthy option?: a 12- to 18-year follow-up study.

To determine whether MoM THA with a small head is still worthy of use, we investigated survivorship, complications, and factors influencing failure. Of 149 consecutive patients (195 hips), 141 (180 hips) of mean age 43 (19-55) years were available for review at a mean of 14.4 years postoperatively. Survivorship for cup revision for any cause was 97.8% at 18.4 years postoperatively. Nine hips generated complaints of groin pain; six showed periacetabular osteolysis, one had pain without radiological change, and two were diagnosed as symptomatic pseudotumors. Four of six hips with periacetabular osteolysis or aseptic loosening were revised. Surgery- and patient-related factors had no effect in results. Our results are encouraging, however, further study will be necessary to determine the incidence and fates of pseudotumors after MoM THA with a small head.

Anesthetic management of a patient with undiagnosed paraganglioma -a case report-.

Retroperitoneal paragangliomas are uncommon neuroendocrine tumors which are derived from extra-adrenal paraganglioma with various clinical signs and symptoms. Although most extra-adrenal paragangliomas are histologically benign, some tumors can synthesize and secrete excess catecholamine from the tumor. Excessive production of catecholamine causes numerous cardiovascular manifestations such as severe hypertension, cardiomyopathy, cardiac arrhythmias, and even multiorgan failure. It can lead to high risks of morbidity and mortality, especially in patients who are unrecognized or not adequately prepared. We present a female patient who was preoperatively undiagnosed of secreting retroperitoneal paraganglioma that caused cardiac tachyarrhythmia and severe intraopertive hypertension not controlled by usual antihypertensive agents. A secreting extra-adrenal paraganglioma should be included in differential diagnosis for patient who have incidentaloma and show wide range of hypertension with hemodynamic instability that is not well controlled by common antihypertensive drugs.

Chronic exertional compartment syndrome in adductor pollicis muscle: case report.

We report a case of chronic exertional compartment syndrome in the adductor pollicis that was confirmed by measuring elevated compartment pressure. Specific finding of magnetic resonance imaging, increased T2 signal intensity in the involved compartment, was also useful for the diagnosis. Pain was relieved by fasciotomy through a volar approach.

Is bipolar hemiarthroplasty a reliable option for Ficat stage III osteonecrosis of the femoral head? 15- to 24-year follow-up study.

PURPOSE: The long-term results of a bipolar hemiarthroplasty (BHA) for osteonecrosis (ON) of the femoral head have not been favorable. The causes have been attributed to cup migration and osteolysis or groin pain. The purpose of this study was to analyze the long-term outcomes and the survivorships of bipolar hemiarthroplasty applied to Ficat stage III ON. MATERIALS AND METHODS: Between 1985 and 1993, 49 patients (63 hips) underwent cementless BHA for Ficat stage III ON. Of these 49 patients, 43 patients (55 hips) of mean age 42.2 years were available for follow-up review at a mean duration of 20.3 years post operation. Anteroposterior hip serial (including extreme abduction/adduction) radiographs were used to evaluate osteolysis, migration, cartilage wear rate, and the ratio of outer/inner bearing motion (O/I ratio) at the latest follow-up. RESULTS: The mean Harris hip score improved to 80.8 points at the latest follow-up. Survivorship at 24 years was 79 and 69 % with revision for any reason and development of acetabular osteolysis as the end point. Groin pain was present in 20 (36.4 %) of the 55 hips, and isolated groin pain was not a reason for revision. The patients had revision surgery performed, which showed that the cartilage wear rate was significantly high, and that the O/I ratio was significantly low (p < 0.05). CONCLUSION: Survivorship determined in this study was more favorable than that of previous studies, and exceeded expectation. The BHA for Ficat stage III ON is not reliable option anymore, considering low survival rate and high osteolysis developmental rate.

The cartilage degeneration and joint motion of bipolar hemiarthroplasty.

PURPOSE: The outcomes of bipolar hemiarthoplasty for osteonecrosis of femoral head have been disappointing due to cartilage degeneration and osteolysis. We investigated the cartilage degeneration, joint motion, and factors associated with osteolysis. METHODS: We retrospectively reviewed 134 bipolar hemiarthroplasties. The wear rate of acetabular cartilage was calculated. The ranges of motion of outer bearing and inner bearing were determined, and the ratio (O/I ratio) was calculated. RESULTS: The mean degeneration rate of acetabular cartilage was 0.34 ± 0.35 mm/year. We could observe that the outer bearing motion was dominant, but decreased over time. In addition, the degeneration rate of cartilage and the decline rate of outer bearing motion of the osteolysis group were significantly higher than those of the control group. CONCLUSIONS: Close observation is needed in cases of high degeneration rate of cartilage and rapid decline of outer bearing motion due to possibility of osteolysis.