Background. Hallux rigidus is a common condition characterised by first metatarsophalangeal joint (MTPJ) degeneration, pain and limited range of motion (ROM). The gold standard surgical treatment is arthrodesis, providing good pain relief but sacrifices ROM. Recently the Cartiva synthetic cartilage implant (SCI) has been utilised as an interpositional arthroplasty, aiming to reduce pain whilst preserving range of motion. Current evidence for Cartiva SCI is largely based on a single cohort with mixed outcomes. We sought to evaluate the clinical outcomes of Cartiva SCI compared to arthrodesis undertaken in our centre. Methods. Retrospective review of patients undergoing Cartiva SCI or arthrodesis for treating hallux rigidus was conducted. Preoperative arthritis was radiographically graded using the Vanore classification. Patient reported outcomes (PROMs) were assessed using EuroQol 5-dimension score (EQ-5D-5L) and Manchester-Oxford Foot Questionnaire (MOXFQ). Results. Between 2017 and 2020 there were 33 cases (17 Cartiva, 16 arthrodesis, mean age 59.0±9.9 years) with a mean follow up of 2.3 years. For the first MTPJ arthrodesis cohort, the MOXFQ domain scores were: Index 3.9±5.8, Walking/Standing 5.1±7.6, Pain 3.2±5.0, and Social Interaction 2.6±4.0. EQ-5D-5L Index score was 0.828±0.270 and the EQ-VAS was 72.5±23.3. For the Cartiva cohort, the MOXFQ domain scores were: Index 7.7±6.0, Walking/Standing 8.9±7.9, Pain 7.1±5.0, and Social Interaction 6.4±5.4. EQ-5D-5L Index score was 0.631±0.234 and the EQ-VAS was 74.8±20.8. There was no statistically significant difference between any MOXFQ domain or EQ-5D-5L scores. However, a negative trend in MOXFQ domains was identified for the Cartiva group, as well as a reoperation rate of 23.5%. Conclusions. The Cartiva SCI demonstrated no advantage over arthrodesis in PROMs, despite the presumed benefit of preserved ROM. A significant reoperation rate was also observed. Surgeons should be cautious in the use of this novel implant

Aims. Arthroplasty for end-stage hallux rigidus (HR) is controversial. Arthrodesis remains the gold standard for surgical treatment, although is not without its complications, with rates of up to 10% for nonunion, 14% for reoperation and 10% for metatarsalgia. The aim of this study was to analyze the outcome of a double-stemmed silastic implant (Wright-Medical, Memphis, Tennessee, USA) for patients with end-stage HR. Methods. We conducted a retrospective review of 108 consecutive implants in 76 patients, between January 2005 and December 2016, with a minimum follow-up of two years. The mean age of the patients at the time of surgery was 61.6 years (42 to 84). There were 104 females and four males. Clinical, radiological, patient reported outcome measures (PROMS) data, a visual analogue score (VAS) for pain, and satisfaction scores were collected. Results. The survivorship at a mean follow-up of 5.3 years (2.1 to 14.1) was 97.2%. The mean Manchester Oxford Foot and Ankle Questionnaire (MOXFQ) scores improved from 78.1 to 11.0, and VAS scores for pain from 7/10 to 1.3/10. The rate of satisfaction was 90.6%. Three implants (2.8%) required revision; one for infection, one-month postoperatively, and two for stem breakage at 10.4 and 13.3 years postoperatively. There was a 1.9% reoperation rate other than revision, 23.1% of patients developed a minor complication, and 21.1% of patients had non-progressive and asymptomatic cysts on radiological review. Conclusion. We report a 97.2% survivorship at a mean follow-up of 5.3 years with this implant. We did not find progressive osteolysis, as has been previously reported. These results suggest that this double-stemmed silastic implant provides a predictable and reliable alternative with comparable outcomes to arthrodesis for the treatment of end-stage HR. Cite this article: Bone Joint J 2020;102-B(2):220–226

Data is scant on the critical question of whether patients with endstage ankle arthritis are better served by a fusion or a replacement. The STAR trial, a prospective case control study, comparing safety and efficacy of STAR ankle replacement at 24 months for 158 replacements and 66 fusions:. This FDA trial showed the STAR ankle replacement had better function, equivalent pain relief and a higher rate of complications and secondary procedures as ankles treated with fusion. A separate prospective cohort comparison of 200 ankle replacements vs. 94 ankle fusions performed by the collaborative consortium of Canadian Orthopaedic Foot and Ankle Surgeons (COFAS) suggests similar patient oriented outcomes at 24 months. Patients' self-assessment questionnaires do not show significant differences between the two groups. The main medium/long-term concerns with ankle replacement remain component subsidence (especially talar subsidence) and polyethylene wear. Forces across the ankle are considerable, and the orientation of those forces to the underlying trabecular structure are a concern. Whether 2 or 3 part ankles will provide better bearing wear results remains unknown. With older designs, at 10 years the Swedish registry found approximately 60% survivorship. This registry has also shown better survivorship in patients with rheumatoid disease and with increased surgeon experience. More recent results related to the Hintegra and AES components show better midterm (5 year) revision rates in selected surgeons hands, than seen with older designs. A large meta-analysis of ankle fusion and replacement published data by Haddad et al reported a mean nonunion rate of 10%. The main long-term concerns with ankle fusion are limitations of motion, and the development of premature arthritis in adjacent foot joints. In a study of an average of 9 year outcome of the Agility ankle replacement suggested that the incidence secondary arthritis is halved by replacement as compared to fusion

Introduction. Total ankle replacement (TAR) is performed for post-traumatic arthritis, inflammatory arthropathy, osteoarthritis and a range of other indications. The Scottish Arthroplasty Project (SAP) began collection of data on TAR in 1997. In this study, using data from the SAP, we examined the annual incidence of TAR between 1997 and 2015. Implant survivorship and the rate of general and joint-specific complications were also analysed. Methods. We identified 601 patients from a national arthroplasty database who had undergone total ankle replacement between 1997 and 2015 and followed up these patients to a maximum of 20 years. We used established methods of linkage with national hospital episode statistics, population and mortality data to examine the incidence of complications and implant survivorship. Results. There were 601 primary TAR procedures with an overall incidence of 0.6 per 10. 5. population per year. Indications for ankle replacement included: posttraumatic arthritis/osteoarthritis 63%; inflammatory arthropathy 25% and other diagnoses including: haemophilia; haemochromatosis; psoriatic arthritis and avascular necrosis in 12%. The peak incidence was in the 6th decade. There was a female to male ratio of 1:1. The incidence of TAR increased over the study period (r= 0.9, p=< 0.0001). This may be due to a broadening range of indications and patient selection criteria, in turn due to increased surgeon experience with ankle replacement and the evolution of implant design. The overall 10 year survivorship was 90%. The rate of general and implant specific complications was comparable to published literature. Conclusion. This study examines a large number of ankle replacements from an established arthroplasty dataset. The prevalence of TAR has increased over 19 years. Overall survivorship was similar to other published registry data on ankle replacements. Further work will look at the effect of surgeon volume on rate of complications, reoperation and survivorship

Aims

The aim of this study was to capture 12-month outcomes from a representative multicentre cohort of patients undergoing total ankle arthroplasty (TAA), describe the pattern of patient-reported outcome measures (PROMs) at 12 months, and identify predictors of these outcome measures.

Introduction. Arthroplasty for treatment of end stage hallux rigidus is controversial. Arthrodesis remains the gold-standard, but this procedure is not without complications, with up to 10% non-union, 14% re-operation and 10% transfer metatarsalgia rates reported. The aim of this study was to analyse the outcome of the double-stemmed silastic implant (Wright-Medical) for end stage hallux rigidus. Method. We conducted a retrospective review of a consecutive series of 108 silastic 1. st. MTPJ implanted in our Unit (January 2005 – December 2016). Data was collected from our research databases, patient notes, PACS and PROMS. No patient was lost to follow-up. Results. Average age was 60.1 years (range 42–42 years; 104F; 4M). Results show a 98.1% survivorship at an average 5.1 years follow up (range 6 months-12 years). Average pre- and post-operative MOXFQ scores were 78.8/100 and 11.0/100 respectively and VAS scores improved from 7/10 to 1.3/10, with an average post-operative range of movement of 26.3°. Overall satisfaction rate was 90.6%. 2 patients (1.9%) required revision; 1 for early infection (2 months) and 1 for stem breakage (10 years). There were 15 complications (13.9%) in the group, 5 lateral metatarsalgia, 7 patients stiffness and ongoing pain in the index joint occurred in 2.7%. There was a 20% incidence of radiological cyst formation or demarcation, but this was neither progressive, symptomatic, nor affected clinical outcome. Conclusions. The authors believe these results are superior to results of other published implants for hallux rigidus (BioPro and Cartiva). Additionally, these results do not confirm progressive osteolysis, previously reported for this implant in other series, as being a mechanism of failure. Finally, these results suggest the double stemmed silastic 1. st. MTPJ replacement provides a reliable alternative, with at least comparable outcomes, to that of fusion, for the treatment of end stage hallux rigidus

Fusion remains the standard of care and is associated with a high satisfaction rate. But.… fusion generally requires 6 weeks of restricted weight bearing or immobilization. Potential problems include 1) nonunion, 2) malunion, 3) sesamoid pain (from DJD), 4) late onset IP1 DJD. Complete joint replacement has been performed with a number of different designs since the early 1970's. The metal and poly designed implants are associated with a high failure rate, presumably from high shear loads, eccentric axial loads, poor fixation and bone stock problems. Resurfacing of both sides of the joint with a one piece silicone based crosslinked rubber {“silastic”} in rheumatoid patients appears to function better with use of metal grommets to reduce generation of particle debris and foreign body reaction. These silastic implants are still used by surgeons in select low-demand rheumatoid patients. Salvage after failure of any of these total joint replacements can be challenging because of loss of bone stock. 3 other methods are used to resurface the joint in severe OA: 1) resurfacing the proximal phalangeal side only, 2) resurfacing the metatarsal head only and 3) resurfacing the joint with and interposition arthroplasty. 1) advantage of the proximal phalangeal side resurfacing is simplicity of geometry; the disadvantage is disruption of the FHB attachment and the relative scarcity of severe cartilage damage at that side of the joint. 2) Advantage of the metatarsal head side for resurfacing is that is the typical location of the arthritic change; the disadvantage is potential interference with the sesamoid complex and bulkiness of fixation could lead to a more difficult salvage. 3) The advantage of interposition arthroplasty is the maintenance of bone stock; disadvantages include inconsistent local tissue and somewhat less predictable outcomes. In this talk I will focus primarily on the technique and results of a proximal phalangeal resurfacing approach for OA of the MTP1 joint

Aim. To examine the mid-term survival, clinical and patient reported outcomes of the silastic 1. st. metatarsophalangeal joint replacement for the treatment of end stage hallux rigidus. Methods. We reviewed 83 consecutive silastic arthroplasties performed in 79 patients for end stage hallux rigidus. There were 3 men and 76 women; mean age 63 years (range 45–78 years). No patient was lost to follow up. Average follow-up was 5.3 years (1.1–11.3 years). The EQ 5D–5L Health index, Manchester-Oxford Foot Questionnaire (MOXFQ), visual analogue scale (VAS) of pain and overall satisfaction rate (Likert scale) were collected for patient reported outcomes. Results. 2 patients required revision; 1 for early infection (2 months) and 1 for stem breakage (10 years 1 month). 5 patients reported lateral metatarsalgia, 2 patients reported neuropathic pain, 6 patients developed superficial infection which fully responded to oral antibiotics, and 1 patient developed interphalangeal joint pain. 2 patients died in the cohort. Pre-operative mean MOXFQ was 44, mean EQ5D Index was 0.564 and VAS was 6.97. At mean follow-up of 5.3 years, the mean MOXFQ was 12.7 (0–57), the mean EQ5D Index was 0.851 (−0.02–1) and the mean VAS was 1.67 (0–8). The mean range of motion was 35° (30° dorsiflexion and 5° plantarflexion). The overall satisfaction rate was 90.2%. The implant survival rate was 97.6%. Conclusions. The silastic big toe arthroplasty offers excellent clinical mid term survival and functional outcomes and could be considered as an attractive alternative to traditional fusion for end stage hallux rigidus

Introduction:. This study evaluates the mid-term results of first metatarsophalangeal joint replacement (MTPJR) for hallux rigidus using the Toefit-Plus™ prosthesis. Methods:. We prospectively studied the outcomes of 86 MTPJR in 73 patients using the AOFAS-HMI score and radiological follow up over a period from 2006 to 2013, with surgeries performed by a single surgeon at two centres. Patients were reviewed, scored and radiographs obtained pre-operatively and then at intervals of 6 weeks, 6 months, 12 months and then yearly. The mean follow up was 33 months (2–72). Results:. The mean AOFAS score of the patients not requiring revision at 1 year was 92, at 2 years was 94, at 3 years was 91, at 4 years was 99, at 5 years was 93, at 6 years was 100 and at 7 years was 97. 18 joints have either been revised or listed for revision giving a revision rate of 21%; this occurred at a mean of 33 months post-surgery. Reasons for revision included loosening of components in 13, infection in 1, dislocation in 2, malalignment in 1 and persistent pain in 1. Eight patients sustained intra-operative fractures requiring circlage wiring, of which 7 went on to union and one required revision. 25 patients had evidence of radiological loosening of which 22 were around the phalangeal component and 3 were around the metatarsal component. Conclusions:. First MTPJ replacement resulted in improved outcomes in patients with hallux rigidus who do not require revision in the medium term, however the revision rate is unacceptably high and as such we have discontinued use of this prosthesis. Radiological loosening of the components is high and needs monitoring for progression which may necessitate revision

Freiberg's Infraction; osteonecrosis of the metatarsal head, is the fourth most common intra-articular osteonecrosis in the body. Surgical intervention is usually reserved for late stage of the disease process (III-V) or failure of conservative management. We evaluated the outcomes of patients treated with primary Interpositional Arthroplasty technique using periosteum and fat for adequate surfacing and as a spacer for Freiberg's Disease. Twenty-three cases (21 patients) were performed from February 2009 – March 2016 (18 women, 5 men). Mean age at surgery was 51.1 years (range 19 – 70.5 years) with 91% affecting the second metatarsal. Twenty-one cases were primary and two cases were revision. Five cases were stage III, 10 were in stage IV and 8 were stage V. All patients underwent Interpositional Arthroplasty using periosteum and fat graft from affected metatarsal inserted as joint spacer and secured with sutures. Patients were followed up by postal questionnaires using two validated questionnaires; MOXFQ and AOFAS. Mean follow-up was 3.7 years (0.6 – 7.6 years). Paired two-tailed student t tests were used to assess clinical significance. The left and right foot was affected in 12 and 11 cases respectively. There were no postoperative infections, non-unions or transfer metatarsalgia. Surgery allowed 8 patients to wear normal footwear, 9 wearing fashion shoes, 5 wearing dress shoes and 5 patients returned to sporting activities. Mean pre-operative and post-operative VAS pain scores were 6.7 (range 4–10) and 3.2 (range 0–0) (p< 0.05). Mean peri-operative AOFAS scores were 43.8 (range 14–14) and 71.3 (range 10–10) (p< 0.05). Mean peri-operative MOXFQ scores were 62.9 (range 23–23) and 31.8 (range 0–0) (p< 0.05). We recommend our novel Interpositional Arthroplasty using periosteum and fat spacer for late stage Freiberg's disease as it can result in significant improvement in pain, prevents donor site morbidity and produces significant functional improvement and patient satisfaction

Aims

This scoping review aims to identify patient-related factors associated with a poorer outcome following total ankle arthroplasty (TAA).

Introduction. Excision of prominent metatarsal heads for severe rheumatoid forefoot deformity is well established in clinical practice but results may deteriorate with time. The Stainsby forefoot arthroplasty however, recognises the pathological anatomy of the deformity and is designed to preserve the metatarsal heads by repositioning the plantar plates and forefoot fat pad underneath them. Design. A prospective case series observing the clinical outcomes and changes in pedobarograph patterns in rheumatoid arthritis patients with severe deformity undergoing Stainsby forefoot arthroplasty. Materials and methods. Twelve patients (21 operated feet) were reviewed at 5 years. AOFAS scores and pedobarographs were recorded pre-operatively and at 5 years post-operatively. Results. AOFAS scores improved significantly from 21 ± 15 pre-operatively to 61 ± 12 at 5 years (p<0.0001) with most of the improvement occurring in the pain score. Pre-operative pedobarographs showed a concentration of forefoot loading, either under the 1st metatarsal or metatarsals 2 and 3, in 38% of patients. Post-operatively there was a significant reduction of peak loading under the 1st metatarsal and metatarsals 2 and 3 and a more even distribution of loading under the forefoot. The duration of the forefoot stance phase as a percentage of total stance phase improved from 24% pre-operatively to 31% post-operatively. Conclusions. Patient reported outcomes indicate the Stainsby procedure provides increased function and lasting pain relief. This is further supported by pedobarograph data showing improvement in the pressure distribution and stance times during gait. We therefore recommend this procedure for management of severe rheumatoid forefoot deformity

Background. Short term results of silastic implant of first MTPJ are successful. However reservations exist regarding long term results. The aim of this study is to evaluate long term outcome of silastic implant prosthesis in treatment of hallus rigidus. We reviewed 108 feet in 83 patients who were operated on between 1988 and 2003. Mean age at operation = 55(SD 8.1). Mean follow up = 8.31 years (SD 3.3). Patients were assessed using the American Orthopaedic Foot and Ankle Scoring system (AOFAS). Passive and active arc of motion were measured. To assess patients' satisfaction they are asked if they would repeat the procedure and also using a visual analogue scale (VAS) to express their overall satisfaction with the outcome. All the patients had anteroposterior and oblique views. Radiographs were assessed for loosening and osteolysis. Results. Median AOFAS = 81(IQR = 15). Median VAS = 8(IQR = 3). Median active arc of motion = 35(IQR 18). Passive arc of motion = 46(IQR = 23). No significant difference in results was found in patients with associated hallux valgus (p value = 0.6). There was significant correlation between the AOFAS and VAS (Pearson correlation = 0.58, p value <.0001). No correlation was found between AOFAS, VAS and radiological changes (P value = 0.8 and 0.9 respectively). In 83 feet (76.9%) patients reported “yes” that they would repeat the procedure and in 22(20.4%) feet patients reported “no”. Prosthesis were removed in three feet at three, five and seven years respectively because of persistent pain. Radiologically, 58% showed cyst formation but didn't correlate with functional outcome. Discussion and Conclusion. This study provides the largest cohort in the literature and the longest follow up. We can conclude that silastic implant arthroplasty is an effective procedure in hallux rigidus management with satisfactory functional outcome and high patient satisfaction

Introduction. There are a number of options available for surgical management of hallux rigidus. Ceramic implants of the first metatarsophalangeal joint (MTPJ) have been available for years; however there are no published long-term results existing. Methods. We performed a retrospective review of all consecutive first MTPJ replacements carried out for later stage hallux rigidus using second generation MOJE ceramic implant with press-fit design. Two specialised foot and ankle surgeons performed these operations at a tertiary referral centre. Patient underwent regular follow ups including clinical review, functional scoring (AOFAS and FFI) and assessment of radiographs. Kaplan Meyer Survival analysis was performed. Results. Our study included 31 prostheses in 24 female patients. Average age at operation was 55.3 years and average follow up time was 80 months. No patients were lost until follow up. Complications included one case of superficial infection and five cases of revision, reasons being fracture of the prostheses (1), unexplained pain (1), subluxation (1) and loosening/sinkage of the implant (2). Prosthesis survival rate was 85.2% at seven years. Assessment of the radiographs showed considerable sinkage of the prosthesis in 43%, tilting in 33% and loosening of the implant in 40.9%. Average postoperative AOFAS score was 71.6 and the average FFI was 27.7. 84% of the patients were satisfied with the results of their operation. Conclusion. Surgery has failed to preserve the function and increase the range of movement in most cases in the long duration. From the patients perspective however the satisfaction with the procedure suggests a success of the implant. Due to poor radiological results and high revision rate we do not recommend the routine use of this prosthesis and all patients that have this type of prosthesis need regular follow up consultations at least yearly with radiographs to assess the position of the implant

Aims

This is a multicentre, non-inventor, prospective observational study of 503 INFINITY fixed bearing total ankle arthroplasties (TAAs). We report our early experience, complications, and radiological and functional outcomes.

Aims

We report the medium-term outcomes of a consecutive series of 118 Zenith total ankle arthroplasties (TAAs) from a single, non-designer centre.

Salvage of a failed total ankle replacement is technically challenging and although a revision procedure may be desirable, a large amount of bone loss or infection may preclude this. Arthrodesis can be difficult to achieve and is usually associated with considerable shortening of the limb.

We describe a technique for restoring talar height using an allograft from the femoral head compressed by an intramedullary nail. Three patients with aseptic loosening were treated successfully by this method with excellent symptomatic relief at a mean follow-up of 32 months (13 to 50).

Clinicians are often asked by patients, “When can I drive again?” after lower limb injury or surgery. This question is difficult to answer in the absence of any guidelines. This review aims to collate the currently available evidence and discuss the factors that influence the decision to allow a patient to return to driving. Medline, Web of Science, Scopus, and EMBASE were searched using the following terms: ‘brake reaction time’, ‘brake response time’, ‘braking force’, ‘brake pedal force’, ‘resume driving’, ‘rate of application of force’, ‘driving after injury’, ‘joint replacement and driving’, and ‘fracture and driving’. Of the relevant literature identified, most studies used the brake reaction time and total brake time as the outcome measures. Varying recovery periods were proposed based on the type and severity of injury or surgery. Surveys of the Driver and Vehicle Licensing Agency, the Police, insurance companies in the United Kingdom and Orthopaedic Surgeons offered a variety of opinions. There is currently insufficient evidence for any authoritative body to determine fitness to drive. The lack of guidance could result in patients being withheld from driving for longer than is necessary, or returning to driving while still unsafe. Cite this article: Bone Joint J 2013;95-B:290–4

Introduction. When ankle arthroplasty fails the options are revision to arthrodesis or revision to arthroplasty. We report early outcomes of revision procedures for failed total replacement. Methods. Retrospective review of prospectively collected data including post-operative complications, union, survivorship and PROMS scores to compare revision to arthrodesis and revision to arthroplasty. Results. 31 revision procedures (10 revision to arthrodesis and 21 revision to arthroplasty) were performed for failed primary ankle arthroplasty (30 patients) between January 2012 and June 2019. 23 males: 8 females, average age of 68. Indications for revisions were aseptic loosening (13), cysts/lysis (6), pain (5), periprosthetic infection (3), fracture (2), fibula erosion (1), polyethylene dislocation (1). Union rate following arthrodesis was 77.9% after primary revision procedure. Impaction bone grafting technique was utilised in seven patients with a union rate of 83%. Survivorship following revision to arthroplasty was 100% at two years; 87.5% at three years and 75% at four years Failed revision arthroplasty was revised to arthrodesis successfully. Median MOxFQ was 73.5 for the arthrodesis group versus 17 in the arthroplasty group (p=0.02). Median AOS was 87 for the arthrodesis group versus 12 for the arthroplasty group (p=0.04). Discussion. This study demonstrated the potential advantages in the short term of revision arthroplasty over conversion to arthrodesis with statistically significant improvements in MOxFQ and AOS within the first two years following revision

Introduction. Cheilectomy is a recommended procedure for the earlier stages of osteoarthritis of the 1. st. metatarsophalangeal joint. Although good improvement in symptoms have been reported in many studies, the long term performance of this procedure is not well understood. It is thought that a significant number of patients go onto have arthrodesis or joint replacement. We report on a large cohort of patients who received this procedure and report on the complications and mid-term outcome. Methods. This is a retrospective study looking at all patients who underwent cheilectomy for hallux rigidus between November 2007 and August 2018. Departmental database was used to access patient details and outcome measures recorded include: postoperative wound infection, patient reported improvement in pain and the incidence of further surgical interventions like revision cheilectomy and conversion to arthrodesis and arthroplasty. X-rays were studied using PACS to stage the osteoarthritis (Hattrup and Johnson classification). Results. A total of 240 feet in 220 patients (20 bilateral surgeries) were included in the study, there were 164 Females (75%) and 56 Males (25%), the median age was 55 years (range 22–90 years). Radiological assessment showed 89 Stage 1 arthritis(42%), 105 Stage 2 (50%), 17 Stage 3 (8%) and 9 patients were excluded due to unavailable X-rays. 5 patients (2%) had superficial wound infection. There were 16 further surgeries (7%) performed in this cohort, 12 arthrodesis (5%), 3 revision cheilectomy and 1conversion to arthroplasty. 157 patients were found to be pain-free at the latest post-operative visit (77%), 48 reported minimal pain (23%), 15 patients were excluded due to unavailable data. Conclusion. Cheilectomy appears to produce good improvement in pain with a low complication rate. The rate of conversion to arthrodesis/arthroplasty is lower than in many reported studies