Total Talar Replacement: Surgical Technique.

Background: Total talar replacement is a salvage procedure for end-stage osteonecrosis of the talus. A customized total talar implant is designed with use of computed tomography scans of the healthy opposite side and made of alumina ceramic. The use of such an implant is potentially recommended, with a guarded prognosis, for the treatment of traumatic, steroidal, alcoholic, systemic lupus erythematous, hemophilic, and idiopathic pathologies. The talus is surrounded by the tibia, fibula, calcaneus, and navicular bones, which account for a large portion of the articular surface area. Yoshinaga9 reported that alumina ceramic prostheses were superior in terms of congruency and durability of articular cartilage compared with 316L stainless steel in an in vivo test in dogs. Therefore, alumina ceramic is an ideal material for replacement of the talus to preserve postoperative hindfoot mobility. Description: Total talar replacement is performed with the patient in a supine position. The anterior ankle approach is utilized to exteriorize the talus, facilitating dissection of the ligaments and joint capsule attached to talus. The first osteotomy is performed around the talar neck, perpendicular to the plantar surface of the foot. The talar head fragment is then removed. Subsequent talar osteotomies are performed parallel to the first cutting line, at approximately 2-cm intervals. The attaching articular capsule and ligaments are dissected in each step. The removal of the posterior talar bone fragments is succeeded by careful dissection of the ligament and joint capsule under the periosteum. After dissecting the remaining interosseous talocalcaneal ligament, the foot is distally retracted and a customized talar implant is inserted. After testing and confirming the stability and mobility of the implant, the wound is irrigated with use of normal saline solution. A suction drain is placed anterior to the implant, and the skin is closed after repairing the extensor retinaculum. Alternatives: In cases with a limited area of necrosis, symptoms may improve with a patellar tendon-bearing brace. However, in many cases of symptomatic osteonecrosis of the talus, nonoperative treatment is not expected to improve symptoms. Alternative surgical procedures include ankle arthrodesis and hindfoot arthrodesis, but there are risks of nonunion, leg-length discrepancy as a result of extensive bone loss, and functional decline because of loss of hindfoot motion. Rationale: Total talar replacement is a fundamentally unique treatment concept in which the entire talus is replaced with an artificial implant. Compared with ankle or hindfoot arthrodesis, this procedure preserves the range of motion of the foot and allows for earlier functional recovery. Postoperative results were satisfactory in the subjective evaluation, with no failure requiring revision. This procedure reduces the risk of postoperative failure in patients who are elderly and/or have underlying diseases, who often require a long recovery time. As the talus is a small bone with uniquely vulnerable vascularity, treatment of talar pathology is usually difficult; however, total talar replacement is a potential treatment option for patients with end-stage osteonecrosis of the talus without obesity. Expected Outcomes: The greatest advantage of total talar replacement is the preservation of ankle and hindfoot mobility. Second, a customized talar prosthesis based on a mirrored model of the contralateral, unaffected talus will allow the smooth transfer of body weight from the lower leg to the heel and forefoot-a requirement for a stable gait. Third, the artificial talar prosthesis has a potential advantage in that it minimizes leg-length discrepancy, preventing daily inconvenience for the patient. Twenty years after the development of the implant, replacement with a total talar prosthesis resulted in a median score of 97 out of 100 on the Japanese Society for Surgery of the Foot (JSSF) Ankle-Hindfoot Scale as an objective evaluation and yielded a significant improvement in the subjective evaluation of the Ankle Osteoarthritis Scale (AOS) in a follow-up study over 10 years. The median ankle joint range of motion was 45°, and complications requiring implant replacement never occurred. Important Tips: The skin incision should be placed at the center of the inferior tibial articular surface and curved medially to avoid the medial branch of the superficial peroneal nerve.During the resection of the talus, the attaching ligament and joint capsule are recommended to be debrided prior to osteotomy.Bone fragments should be removed as an entire block in order to avoid leaving small fragments.When inserting the artificial talus, pull the entire foot distally by grasping the heel in order to avoid excessive plantar flexion.During wound closure, the extensor retinaculum should be repaired to avoid skin bowstringing.Although favorable long-term results have been reported, postoperative outcomes in patients with high body mass index have not been adequately investigated. This procedure should be carefully selected on the basis of the physical characteristics of the patient. Acronyms and Abbreviations: AVN = avascular necrosis (osteonecrosis)SLE = systemic lupus erythematousCAD = computer-aided designCT = computed tomographyJSSF = Japanese Society for Surgery of the FootIQR = interquartile rangeAOS = Ankle Osteoarthritis ScalePWB = partial weight-bearingW = weeks.

Reconstruction after Talar Tumor Resection: A Systematic Review.

This systematic review investigated the functional outcomes and complications of reconstruction methods after talar tumor resection. A systematic search of PubMed, Embase, and the Cochrane Central Register of Controlled Trials databases identified 156 studies, of which 20 (23 patients) were ultimately included. The mean Musculoskeletal Tumor Society scores in the groups reconstructed using tibiocalcaneal fusion (n = 17), frozen autograft (n = 1), and talar prosthesis (n = 5) were 77.6 (range 66-90), 70, and 90 (range 87-93), respectively. Regarding complications, sensory deficits were observed in one patient (6%) and venous thrombosis in two patients (12%) in the tibiocalcaneal fusion group, while osteoarthritis was observed in one patient (100%) in the frozen autograft group. No complications were observed in the talar prosthesis group. Reconstruction with talar prosthesis seems preferable to conventional tibiocalcaneal fusion after talar tumor resection because it offers better function and fewer complications. However, as this systematic review included only retrospective studies with a small number of patients, its results require re-evaluation in future randomized controlled trials with larger numbers of patients.

The Long-Term Clinical Results of Total Talar Replacement at 10 Years or More After Surgery.

BACKGROUND: Total talar replacement has been reported to have favorable short-term and intermediate-term results for the treatment of osteonecrosis of the talus. The purpose of this study was to evaluate the long-term clinical results of total talar replacement for a minimum of 10 years after the surgical procedure. METHODS: From October 2005 to April 2011, 19 ankles in 18 patients (1 male and 17 female) were treated using a total talar prosthesis for osteonecrosis of the talus. The median follow-up period was 152 months (interquartile range [IQR], 138, 160 months). The Ankle Osteoarthritis Scale (AOS) score, the Japanese Society for Surgery of the Foot (JSSF) Ankle-Hindfoot Scale score, and the presence of osteophytes and degenerative changes in the adjacent joints were assessed preoperatively and at the final follow-up. Subsidence of the prosthesis was also assessed at the earliest opportunity for full weight-bearing and the final follow-up. The postoperative range of motion of the ankle was assessed at the final follow-up. RESULTS: The median scores for all subscales of the AOS significantly improved. The median JSSF Ankle-Hindfoot Scale score significantly improved from 58 (IQR, 55, 59.5) to 97 (IQR, 87, 99.5). In the subcategories of this scale, the median pain score improved from 20 (IQR, 20, 20) to 40 (IQR, 30, 40), and the median function score improved from 28 (IQR, 26, 30.5) to 47 (IQR, 47, 50). The median postoperative range of motion of the ankle was 45° (IQR, 42.5°, 55°). Subsidence of the implant was not recognized at the final follow-up (p = 0.083). Proliferation of osteophytes and degenerative changes in the adjacent joints did not affect the overall results. CONCLUSIONS: The customized alumina ceramic total talar prosthesis produced stable clinical outcomes over 10 years, and the patients treated with total talar replacement showed favorable clinical results over this time frame. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Ceramic Artificial Talus as the Initial Treatment for Comminuted Talar Fractures.

BACKGROUND: Comminuted talar fractures are rare. Generally, this fracture occurs as a result of high-energy injuries. Therefore, this operation is challenging for the surgeon. We started to replace the whole talus with a total talar prosthesis in cases of aseptic talar necrosis in 2005. Based on these results, replacement with a ceramic artificial talus was performed as the initial treatment for comminuted talar fractures. METHODS: From 2009 to 2016, a total of 6 feet of 6 patients with comminuted talar dome fractures or talar body defects were replaced with a ceramic artificial talus. The patients' mean age was 40.3 years (range, 19-59). Postoperative assessments were performed in accordance with the American Orthopaedic Foot & Ankle Society (AOFAS) ankle/hindfoot score system. Postoperative range of motion and sports activities were also evaluated. Follow-up ranged from 12 to 84 (mean, 46.8) months. RESULTS: The postoperative AOFAS score was on average 78.8 (64-100). The postoperative range of motion was on average 10 degrees (5-20) for dorsiflexion and 31 degrees (15-50) for plantarflexion. Three patients had returned to sport activities. CONCLUSION: Prosthetic total talar replacement was a useful procedure for patients with comminuted talar fractures, which had good congruency of the custom-made implant with the adjacent joints, resulting in stability, and maintained ankle function. Furthermore, this procedure could prevent the complications of long-term external fixation and non-weight-bearing walking seen after open reduction and arthrodesis. LEVEL OF EVIDENCE: Level IV, retrospective comparative study.

Synovial Metallosis After Ceramic Total Ankle Arthroplasty Treated With a Total Talar Prosthesis: A Case Report.

Total ankle arthroplasty is a useful surgical procedure for osteoarthritis of the ankle, but aseptic loosening of components is an issue. We report here a case of aseptic implant loosening with metallosis after total ankle arthroplasty using the TNK ankle (Kyocera, Kyoto, Japan), which occurred despite the components being ceramic. We also report favorable results from our method of treatment using a total talar prosthesis in the revision surgery. During the revision surgery, synovial metallosis was found, probably related to superficial damage to the screw affixing the tibial component to the bone. Because both the tibial and talar components were loose, all the components and the remaining talar bone were removed. A new tibial component and a custom-made alumina-ceramic total talar prosthesis was inserted. Pain relief was achieved and maintained through the latest follow-up visit at 42 months after revision surgery. Dorsiflexion of the ankle improved from 0° to 5° and plantarflexion remained unchanged from its preoperative range of 20°. The American Orthopaedic Foot & Ankle Society ankle-hindfoot score improved from 38 to 80 points. To the best of our knowledge, this is the first reported case of an alumina-ceramic total ankle prosthesis loosening caused by metallosis resulting from screw abrasion. Favorable treatment results were obtained by using a total talar prosthesis in the revision surgery.

Short-term efficacy and safety of hyaluronic acid injection for plantar fasciopathy.

PURPOSE: Plantar fasciopathy is the most common cause of plantar heel pain and is considered to be a type of enthesopathy. The short-term efficacy, safety, and dose-response relationship of high-molecular-weight hyaluronic acid (HA) was investigated in patients with plantar fasciopathy. METHODS: In this multicenter, prospective, randomized, double-blind, placebo-controlled trial, 168 patients with persistent pain from plantar fasciopathy for more than 12 weeks were randomly assigned to receive 2.5 mL of 1% HA (H-HA), 0.8 mL of 1% HA (L-HA), or 2.5 mL of 0.01% HA (control group) once a week for 5 weeks. The primary endpoint was improvement in visual analogue scale (VAS) score for pain from baseline to week 5. RESULTS: The VAS scores (least squares mean ± standard error) in each group decreased gradually after the start of treatment, a change of -3.3 ± 0.3 cm for the H-HA group, -2.6 ± 0.3 cm for the L-HA group, and -2.4 ± 0.3 cm for the control group, with the H-HA group improving significantly more than the control group (P = 0.029). No serious adverse events were reported. There was no difference between the groups in the incidence rates of adverse drug reactions. CONCLUSION: The administration of five injections of high-molecular-weight HA is an effective treatment with no serious adverse drug reactions and is a conservative treatment option for plantar fasciopathy. This treatment contributed to alleviation of pain in patients with plantar fasciopathy and improvement in their activities of daily living. LEVEL OF EVIDENCE: I.

Total Talar Replacement for Idiopathic Necrosis of the Talus: A Case Report.

Idiopathic osteonecrosis of the talus is a rare but severe condition that directly affects the ability to walk and is difficult to treat either conservatively or surgically. We report the case of a 72-year-old female with idiopathic necrosis of the talus treated with total talar replacement surgery. A custom-made aluminum-ceramic total talar prosthesis was prepared using the mirror image of the computed tomography and radiographic data from the contralateral ankle. The talus was exposed and removed using an anterior approach, and the total talar prosthesis was inserted. The prosthesis was placed in a stable position between the tibia, calcaneus, and navicular, with no signs of instability with ankle joint movement. The ankle was immobilized in a short-leg cast for 3 weeks. At the latest follow-up examination, 2 years after surgery, the patient was walking without pain. Examination of the left ankle showed 20° of dorsiflexion and 40° of plantar flexion. The American Orthopaedic Foot and Ankle Society ankle/hindfoot score was 90, which had improved from a preoperative score of 45. Radiographic examination showed that the prosthesis was in a stable position in the ankle mortise, and no degenerative or destructive changes were observed in the surrounding bones. This is the first reported case of total talar replacement with a prosthesis for idiopathic talar necrosis. Although the long-term outcome is still unknown, this procedure could provide a good treatment option for idiopathic necrosis of the talus.

An Alumina Ceramic Total Talar Prosthesis for Osteonecrosis of the Talus.

BACKGROUND: Treatment of osteonecrosis of the talus is challenging. Total talar replacement has the potential to restore the function of the ankle joint without an associated leg-length discrepancy. The purpose of the present study was to investigate postoperative function and pain after total talar replacement in patients with osteonecrosis of the talus. METHODS: Fifty-five ankles in fifty-one consecutive patients with osteonecrosis of the talus who were treated with a total talar replacement from 2005 to 2012 were included in the investigation. Scores according to the Japanese Society for Surgery of the Foot (JSSF) ankle-hindfoot scale and the Ankle Osteoarthritis Scale (AOS) were assessed before surgery and at the final follow-up evaluation. RESULTS: According to the JSSF ankle-hindfoot scale, the score for pain improved from a mean (and standard deviation) of 15 ± 9.4 points (range, 0 to 20 points) to 34 ± 5.6 points (range, 20 to 40 points); the score for function, from 21.2 ± 9.7 points (range, 4 to 38 points) to 45.1 ± 4.0 points (range, 37 to 50 points); the score for alignment, from 6.0 ± 2.8 points (range, 5 to 10 points) to 9.8 ± 0.9 points (range, 5 to 10 points); and the total score, from 43.1 ± 17.0 points (range, 11 to 68 points) to 89.4 ± 8.4 points (range, 76 to 100 points). According to the AOS scale, the score for "pain at its worst" improved from a mean of 6.1 ± 3.3 points (range, 0 to 9.9 points) to 2.0 ± 1.7 points (range, 0 to 6.3 points). CONCLUSIONS: Prosthetic talar replacement is a useful procedure for patients with osteonecrosis of the talus as it maintains ankle function.

Surgical management of the peroneus quartus muscle for bilateral ankle pain: a case report.

The peroneus quartus muscle is an accessory muscle seen in the lateral compartment of the lower leg. Although the peroneus quartus muscle is asymptomatic in general, it sometimes becomes pathologic. We present the rare case of bilateral ankle pain with crepitation caused by the peroneus quartus muscle. Magnetic resonance imaging should be considered to assist with diagnosing this condition. Foot and ankle surgeons should consider it in the preoperative differential diagnosis when patients present with posterior ankle pain.

Differences in elements between intact and disrupted human ligamenta capitum femorum.

To compare the element compositions between intact (i.e., intact throughout its length) and disrupted (i.e., ligament no longer attached to the attachment) ligaments, the contents of elements in the human ligamenta capitum femorum (LCF) were analyzed by inductively coupled plasma-atomic emission spectrometry. Histological and immunohistological assessments were also performed in both groups. The subjects were 8 men and 32 women. Trace element analyses showed that the sulfur and iron contents were significantly greater in the intact group than in the disrupted group, while the phosphorus and magnesium contents were significantly smaller in the intact group than in the disrupted group. The calcium and zinc contents were smaller in the intact group than in the disrupted group, with no significant differences. Histologically, there were fibrocartilage cells and extracellular matrix metachromasia in ligaments of the intact group. In contrast, fibrocartilage cells disappeared, and fat cells appeared instead of collagen fibrils in ligaments of the disrupted group. The LCFs of the intact group were immunohistologically positive for all components examined including collagens, glycosaminoglycans, and proteoglycans. The increase in sulfur suggested the presence of high glycosaminoglycan levels associated with fibrocartilaginous metaplasia in the ligament by compressive force. The reduction in iron may show a decreased number of blood vessels in the synovium after ligament disruption. The increases in phosphorus, magnesium, and calcium are indicative of degenerative changes including calcification and ossification. We conclude that differences in the contents of elements between intact and disrupted LCFs indicate degenerative alterations to the ligament structure after disruption.

The short-term effect after a single injection of high-molecular-weight hyaluronic acid in patients with enthesopathies (lateral epicondylitis, patellar tendinopathy, insertional Achilles tendinopathy, and plantar fasciitis): a preliminary study.

BACKGROUND: Hyaluronic acid (HA) with a high molecular weight of 2700 kDa is approved in Japan to treat osteoarthritis of the knee, periarthritis scapulohumeralis, and knee pain associated with rheumatoid arthritis. The purpose of this preliminary study was to investigate the short-term efficacy, safety, and injectable volume of HA in the treatment of enthesopathies. METHODS: A total of 61 patients (16 with lateral epicondylitis, 14 with patellar tendinopathy, 15 with insertional Achilles tendinopathy, and 16 with plantar fasciitis) were each administered a single injection of HA (up to 2.5 ml). Efficacy and safety were assessed by comparing the visual analog scale (VAS) for pain and local symptoms before injection (baseline) and at 1 week after injection. We also investigated the injectable volume by means of the difference in syringe weight before and after injection and by the judgment of the administering investigator. RESULTS: The injection of HA resulted in a change in VAS (mean ± SD) of -2.20 ± 2.26 cm for the four sites overall and -2.55 ± 2.43 cm for lateral epicondylitis, -2.01 ± 2.16 cm for patellar tendinopathy, -1.80 ± 1.91 cm for insertional Achilles tendinopathy, and -2.38 ± 2.61 cm for plantar fasciitis. The injection of HA also improved local symptoms in each site. It was also determined that 2.5 ml of HA can be injected in each of the four sites. CONCLUSION: A single injection of HA resulted in similar improvements of pain in each of the four enthesopathies (lateral epicondylitis, patellar tendinopathy, insertional Achilles tendinopathy, and plantar fasciitis). These results suggest that HA could be clinically effective in the treatment of enthesopathies.

Superficial blood flow of the superior labrum associated with rotator cuff tear using laser Doppler flowmeter.

INTRODUCTION: Superior labrum anterior and posterior (SLAP) lesions due to overuse by repeated pitching motion and trauma are often noted and usually. However, shoulder disorders with a chronic course are often accompanied by SLAP lesions. SLAP lesions are frequently observed during arthroscopic surgery of the shoulder joint for rotator cuff tear in middle-aged and elderly individuals, suggesting the involvement of factors other than pitching motion and traumatic events in the pathogenesis. We considered that blood flow in the labrum is altered. The purpose of this study was to clarify the superficial blood flow in the superior labrum during arthroscopic surgery of the rotator cuff tear and investigate whether it is altered with labrum injury. MATERIALS AND METHODS: We evaluated 33 subjects with a mean age of 55.1 years who underwent arthroscopic surgery for partial or complete rotator cuff tears. The blood flow measurement site for the superior labrum was set at the supraglenoid tubercle attachment site, and blood flow was measured twice using laser Doppler flowmeter. The mean was calculated and compared among the normal labrum and type 1 SLAP lesions. RESULTS: The morphology of the labrum was normal in 16 subjects, and 17 subjects had type 1 SLAP lesions. The mean blood flow was 1.75 ml/min/100 g in subjects with a normal labrum; however, in subjects with type 1 SLAP lesions, blood flow was 1.32 ml/min/100 g, showing significant differences (P < 0.01). CONCLUSION: Superficial blood flow in the superior labrum of the shoulder with rotator cuff tear was measured using laser Doppler flowmetry. The blood flow in type 1 SLAP lesions was lower than that in the normal labrum.

Functional reconstruction of bilateral injuries to the dorsum of hand using radial forearm tendocutaneous flaps.

We treated a patient with skin and tendon defects of both hands as a result of injury by a heat press. There have been no reports of bilateral hand injuries being treated using simultaneous bilateral tendocutaneous flaps. In this case, we reconstructed the injured tissue using simultaneous bilateral radial forearm tendocutaneous flaps, with satisfactory results.

Ewing sarcoma of the proximal phalanx: case report.

We report a case of primary Ewing sarcoma of the proximal phalanx of the right middle finger in an 18-year-old boy. He was treated with neoadjuvant chemotherapy, followed by ray amputation. To restore maximum function, the index ray was transferred to the base of the third metacarpal bone and fixed with a plate. The function of his right hand after the operation was excellent and the cosmetic appearance acceptable. There was no evidence of local recurrence or metastasis after 20 months follow up.

Ultrasound-guided arthroscope insertion and decompression of a supraspinous fossa cyst.

A cyst arising in the scapular supraspinous fossa may cause shoulder pain; subsequently, enlargement of the cyst may result in severe compression of the adjacent suprascapular nerve, leading to muscle weakness and sensory disorder. Decompression of the nerve through cyst removal is effective in resolving these symptoms. However, treatment can also be performed less invasively through arthroscopy. Insertion of an arthroscope without visual guidance could cause tissue damage and, consequently, would become an invasive procedure itself. The use of ultrasonography to guide the scope to the cyst decreases the invasiveness of the procedure. Here, we present the case of a patient with a cyst arising in the scapular supraspinous fossa, in whom we could relatively readily and safely observe the cyst by advancing an arthroscope under ultrasonographic guidance. The suprascapular nerve was decompressed via cyst removal.

Anatomy of hallux valgus in rheumatoid arthritis: radiographic analysis using a two-dimensional coordinate system.

OBJECTIVE: The purpose of this study is to compare the anatomy of rheumatoid hallux valgus with that of idiopathic hallux valgus from the standpoint of joint-preserving surgery. METHODS: One hundred forty-eight feet of 81 rheumatoid patients were included. Feet with idiopathic hallux valgus and normal feet were compared as controls. Weight-bearing dorsoplantar radiographs of the feet were taken of each patient. A two-dimensional coordinate system was defined on the radiographic image, and 19 anatomic points of the forefoot were measured. RESULTS: In rheumatoid hallux valgus, the first metatarsal head shifted medially as hallux valgus angle increased, which was similar to the deformity of idiopathic hallux valgus. Proximal deviation of the tips of the lesser toes, caused by clawing and dislocations of the metatarsophalangeal joints, occurred in rheumatoid hallux valgus. Specifically the tips of the second toes in rheumatoid hallux valgus were located more proximally than those in idiopathic hallux valgus irrespective of the severity of hallux valgus. CONCLUSIONS: Corrective osteotomy of the first metatarsal is a reasonable procedure for rheumatoid hallux valgus. Additionally, correction of the second toe deformity to make a stable lateral support on the hallux may be another important factor for successful joint-preserving surgery.

Early fixation of cobalt-chromium based alloy surgical implants to bone using a tissue-engineering approach.

To establish the methods of demonstrating early fixation of metal implants to bone, one side of a Cobalt-Chromium (CoCr) based alloy implant surface was seeded with rabbit marrow mesenchymal cells and the other side was left unseeded. The mesenchymal cells were further cultured in the presence of ascorbic acid, ß-glycerophosphate and dexamethasone, resulting in the appearance of osteoblasts and bone matrix on the implant surface. Thus, we succeeded in generating tissue-engineered bone on one side of the CoCr implant. The CoCr implants were then implanted in rabbit bone defects. Three weeks after the implantation, evaluations of mechanical test, undecalcified histological section and electron microscope analysis were performed. Histological and electron microscope images of the tissue engineered surface exhibited abundant new bone formation. However, newly formed bone tissue was difficult to detect on the side without cell seeding. In the mechanical test, the mean values of pull-out forces were 77.15 N and 44.94 N for the tissue-engineered and non-cell-seeded surfaces, respectively. These findings indicate early bone fixation of the tissue-engineered CoCr surface just three weeks after implantation.

A pilot project for the Japan arthroplasty register.

BACKGROUND: National arthroplasty registers are valuable tools for reporting on an updated epidemiologic survey of arthroplasties and for evaluating the performance of implants and operative procedures through the early identification of failure risk factors. More than ten registers have been launched globally, but no national register has been reported in Asia. METHODS: In February 2006, a pilot project of the Japan Arthroplasty Register (JAR) for total hip arthroplasty (THA) and total knee arthroplasty/unicompartmental knee arthroplasty (TKA/UKA) was launched by the Japanese Orthopaedic Association (JOA). Data obtained include information about patients, primary and revision arthroplasty operative procedures, and implants and materials used. The JAR office accumulated and processed all data and reports annually. RESULTS: Up to May 2011, 83 of 130 hospitals nominated by the JOA (64 %) participated in the JAR pilot project. From 2006 to 2011, 33,080 data collection forms were submitted; 17,534 for THA and 17,269 for TKA/UKA. A brief summary of the annual report of the JAR is available from The Japanese Society for Replacement Arthroplasty web site at http://jsra.info/ . CONCLUSION: A national arthroplasty register is a useful tool for evaluating the outcomes of interventions and the materials used in arthroplasties and for providing rapid feedback to practitioners and patients about any failure of THA and TKA/UKA. As the first national arthroplasty register in Asia, the JAR will help guide the development of registers of arthroplasty characteristics specific to Asian populations.

In vivo kinematics and articular surface congruency of total ankle arthroplasty during gait.

Relatively high rates of loosening and implant failure have been reported after total ankle arthroplasty. Abnormal kinematics and incongruency of the articular surface may cause increased contact pressure and rotational torque applied to the implant, leading to loosening and implant failure. We measured in vivo kinematics of two-component total ankle arthroplasty (TNK ankle), and assessed congruency of the articular surface during the stance phase of gait. Eighteen ankles of 15 patients with a mean age of 75±6 years (mean±standard deviation) and follow-up of 44±38 months were enrolled. Lateral fluoroscopic images were taken during the stance phase of gait. 3D-2D model-image registration was performed using the fluoroscopic image and the implant models, and three-dimensional kinematics of the implant and incongruency of the articular surface were determined. The mean ranges of motion were 11.1±4.6°, 0.8±0.4°, and 2.6±1.5° for dorsi-/plantarflexion, inversion/eversion, and internal/external rotation, respectively. At least one type of incongruency of the articular surface occurred in eight of 18 ankles, including anterior hinging in one ankle, medial or lateral lift off in four ankles, and excessive axial rotation in five ankles. Among the four ankles in which lift off occurred during gait, only one ankle showed lift off in the static weightbearing radiograph. Our observations will provide useful data against which kinematics of other implant designs, such as three-component total ankle arthroplasty, can be compared. Our results also showed that evaluation of lift off in the standard weightbearing radiograph may not predict its occurrence during gait.