Aims. The aim of this study was to identify factors that determine outcomes of treatment for patients with chondroblastic osteosarcomas (COS) of the limbs and pelvis. Patients and Methods. The authors carried out a retrospective review of prospectively collected data from 256 patients diagnosed between 1979 and 2015. Of the 256 patients diagnosed with COS of the pelvis and the limbs, 147 patients (57%) were male and 109 patients (43%) were female. The mean age at presentation was 20 years (0 to 90). Results. In all, 82% of the patients had a poor response to chemotherapy, which was associated with the presence of a predominantly chondroblastic component (more than 50% of tumour volume). The incidence of local recurrence was 15%. Synchronous or metachronous metastasis was diagnosed in 60% of patients. Overall survival was 51% and 42% after five and ten years, respectively. Limb localization and wide surgical margins were associated with a lower risk of local recurrence after multivariable analysis, while the response to chemotherapy was not. Local recurrence, advanced patient age, pelvic tumours, and large volume negatively influenced survival. Resection of pulmonary metastases was associated with a survival benefit in the limited number of patients in whom this was undertaken. Conclusion. COS demonstrates a poor response to chemotherapy and a high incidence of metastases. Wide resection is associated with improved local control and overall survival, while excision of pulmonary metastases is associated with improved survival in selected patients. Cite this article: Bone Joint J 2019;101-B:739–744

Aims. We present the clinical and radiographic outcome of 81 children with Gartland type I to III supracondylar humeral fractures at a minimum follow-up of ten years (mean 12.1 years; 10.3 to 16.1) following injury. Patients and Methods. The clinical and functional outcomes are compared with normal age- and gender-matched individuals. The population-based study setting was first identified from the institutional registries; the rate of participation was 76%. Controls were randomly selected from Finnish National Population Registry. Results. According to Flynn's criteria, most fractures (75.3%) resulted in a satisfactory (“good or excellent”) outcome. Satisfactory recovery was achieved in 75.0% of type I fractures treated by closed splinting (p = 0.013). Type II fractures were associated with both satisfactory (57.7%) and unsatisfactory (42.3%) results, regardless of the type of treatment, although the numbers were small in the sub groups. Most type III fractures were treated operatively, and most (76%) had a satisfactory outcome according to Flynn’s criteria (p = 0.015). Compared with none among the normal subjects, flexion of the elbow was reduced by >  10° at long-term follow-up in 20 cases (24.7%, p < 0.001) and 9 (11.1%) had a reduced flexion of > 15° (p = 0.004). In patients who had sustained a type III fracture, the carrying angle was decreased by 35.7% (from 9.8° to 6.3°; p = 0.048). All patients achieved an excellent Mayo Elbow Performance Score (mean 96.4 points). Conclusion. The long-term outcome of extension-type supracondylar humeral fractures is generally good, but not exclusively benign, with the potential for long-term pain and ulnar nerve sensitivity, and a decrease in grip strength and range of movement in type II and type III fractures. Bony remodelling cannot be relied upon to correct any residual deformity. In particular, type II fractures have impaired long-term recovery and justify individual consideration in their treatment. Cite this article: Bone Joint J 2016;98-B:1410–17

Aims. The aim of this study was to evaluate the surgical management and outcome of patients with an acral soft-tissue sarcoma of the hand or foot. Patients and Methods. We identified 63 patients with an acral soft-tissue sarcoma who presented to our tertiary referral sarcoma service between 2000 and 2016. There were 35 men and 28 women with a mean age of 49 years (. sd. 21). Of the 63 sarcomas, 27 were in the hands and 36 in the feet. The commonest subtypes were epithelioid sarcoma in the hand (n = 8) and synovial sarcoma in the foot (n = 11). Results. In 41 patients (65%), the tumour measured less than 5 cm in its largest dimension (median size 3 cm (٢ to ٦)); 27 patients (43%) were diagnosed after inadvertent excision prior to their referral to the specialist sarcoma unit. After biopsy and staging, primary surgical intervention at the sarcoma unit was excision and limb salvage in 43 (68%), partial (digit or ray) amputation in 14 (22%), and more proximal amputation in six (10%). At final follow up, local recurrence had been treated by one partial amputation and six amputations, resulting in a partial amputation rate of 24% and a proximal amputation rate of 19%. The five-year survival rate was 82%. Patients who underwent inadvertent excision showed no statistically significant difference in survival or local recurrence, but were more likely to undergo amputation (p = 0.008). Large tumour size (> 5 cm) was associated with lower survival (p = 0.04) and a higher risk of local recurrence (p = ٠.٠٠٩). Conclusion. Most acral soft-tissue sarcomas measure less than 5 cm at presentation, indicating that while size can be a useful prognostic factor, it should not be used as a diagnostic threshold for referral. Increased tumour size is associated with a higher rate of local recurrence and reduced survival. Sarcoma excision with limb preservation does not result in an increased risk of local recurrence. Cite this article: Bone Joint J 2018;100-B:1518–23

Aims. The aim of this study was to report the implant survival and patient-reported outcome measures (PROMs) in a consecutive series of patients aged less than 50 years at the time of arthroplasty using the Birmingham Hip Resurfacing system (BHR), with a minimum follow-up of ten years. Patients and Methods. A total of 226 patients with osteoarthritis of the hip, who underwent BHR and presented to a single surgeon, were included in the study. Survival of the implant was confirmed by cross-checking with the Australian Orthopaedic Association National Joint Replacement Registry. Kaplan–Meier survival curves with 95% confidence intervals (CIs) were constructed. Pre- and postoperative PROMs were compared with t-tests, and postoperative scores were compared using anchor analysis with age and gender matched normative data. Results. At median follow-up of 12 years (interquartile range (IQR) 10 to 13), six BHRs were revised, with a cumulative rate of survival of 96.8% (95% confidence interval (CI) 94.2 to 99.4) at 15 years, and with a significantly lower (p = 0.019) cumulative rate of revision than the national average for the same device at ten years. Most revisions (n = 4) were undertaken early, less than three years postoperatively, and occurred in women. Patient-reported general health (Veteran’s Rand-36), disease state (Western Ontario and McMaster Universities Osteoarthritis Index), function (modified Harris Hip Score) and level of activity (Tegner activity score) maintained significant (p < 0.01 for each) improvements beyond ten years postoperatively and were equal to, or exceeded, age- and gender-matched normative data in more than 80% of the patients. Conclusion. Longer term PROMs after BHR, from a single surgeon, for patients aged less than 50 years remain under-reported. We found that the outcome after a BHR, at a minimum of ten years postoperatively, remained satisfactory, particularly for self-reported hip function

Aims

To determine the relationship between articular cartilage status and clinical outcomes after medial opening-wedge high tibial osteotomy (MOHTO) for medial compartmental knee osteoarthritis at intermediate follow-up.

Aims. The primary aim of this study was to quantify the improvement in patient-reported outcome measures (PROMs) following total hip arthroplasty (THA), as well as the extent of any deterioration through the seven-year follow-up. The secondary aim was to identify predictors of PROM improvement and deterioration. Patients and Methods. A total of 976 patients were enrolled into a prospective, international, multicentre study. Patients completed a battery of PROMs prior to THA, at three months post-THA, and at one, three, five, and seven-years post-THA. The Harris Hip Score (HHS), the 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS), the SF-36 Mental Component Summary (MCS), and the EuroQol five-dimension three-level (EQ-5D) index were the primary outcomes. Longitudinal changes in each PROM were investigated by piece-wise linear mixed effects models. Clinically significant deterioration was defined for each patient as a decrease of one half of a standard deviation (group baseline). Results. Improvements were noted in each PROM between the preoperative and one-year visits, with one-year values exceeding age-matched population norms. Patients with difficulty in self-care experienced less improvement in HHS (odds ratio (OR) 2.2; p = 0.003). Those with anxiety/depression experienced less improvement in PCS (OR -3.3; p = 0.002) and EQ-5D (OR -0.07; p = 0.005). Between one and seven years, obesity was associated with deterioration in HHS (1.5 points/year; p = 0.006), PCS (0.8 points/year; p < 0.001), and EQ-5D (0.02 points/year; p < 0.001). Preoperative difficulty in self-care was associated with deterioration in HHS (2.2 points/year; p < 0.001). Preoperative pain from other joints was associated with deterioration in MCS (0.8 points/year; p < 0.001). All aforementioned factors were associated with clinically significant deterioration in PROMs (p < 0.035), except anxiety/depression with regard to PCS (p = 0.060). Conclusion. The present study finds that patient factors affect the improvement and deterioration in PROMs over the medium term following THA. Special attention should be given to patients with risk factors for decreased PROMs, both preoperatively and during follow-up. Cite this article: Bone Joint J 2019;101-B:768–778

Aims. The direct posterior approach with subperiosteal dissection of the paraspinal muscles from the vertebrae is considered to be the standard approach for the surgical treatment of adolescent idiopathic scoliosis (AIS). We investigated whether or not a minimally-invasive surgery (MIS) technique could offer improved results. Methods. Consecutive AIS patients treated with an MIS technique at two tertiary centres from June 2013 to March 2016 were retrospectively included. Preoperative patient deformity characteristics, perioperative parameters, power of deformity correction, and complications were studied. A total of 93 patients were included. The outcome of the first 25 patients and the latter 68 were compared as part of our safety analysis to examine the effect of the learning curve. Results. In the first 25 cases, with a mean follow-up of 5.6 years (standard deviation (SD) 0.4), the mean preoperative major Cobb angle was 57.6° (SD 9.8°) and significantly corrected to mean 15.4° (SD 5.6°, 73% curve correction). The mean preoperative T5-T12 was 26.2 (SD 12.8) and significantly increased to mean 32.9 (SD 8.3). Both frontal and sagittal plane correction was conserved two years after surgery. The rate of perioperative complications was 12% and three further complications occurred (three deep delayed infection). In the latter cases, 68 patients were included with a mean follow-up time of three years (SD 0.6). The mean preoperative major Cobb angle was 58.4° (SD 9.2°) and significantly corrected to mean 20.4° (SD 7.3°).The mean preoperative T5-T12 kyphosis was 26.6° (SD 12.8°) and was significantly increased to mean 31.4° (SD 8.3°). Both frontal and sagittal correction was conserved two years after surgery. The perioperative (30 day) complication rate was 1.4%. Two (2.9%) additional complications occurred in two patients. Conclusion. MIS for AIS is associated with a significant correction of spine deformity in the frontal and sagittal planes, together with low estimated blood loss and short length of stay. The perioperative complication rate seems to be lower compared with the standard open technique based on the literature data. The longer-term safety of MIS for AIS needs to be documented with a larger cohort and compared with the standard posterior approach. Cite this article: Bone Joint J 2020;102-B(4):506–512

Aims

Fixation of scaphoid nonunion with a volar locking plate and cancellous bone grafting has been shown to be a successful technique in small series. Few mid- or long-term follow-up studies have been reported. The aim of this study was to report the mid-term radiological and functional outcome of plate fixation for scaphoid nonunion.

Aims. It is not known whether change in patient-reported outcome measures (PROMs) over time can be predicted by factors present at surgery, or early follow-up. The aim of this study was to identify factors associated with changes in PROM status between two-year evaluation and medium-term follow-up. Patients and Methods. Patients undergoing Birmingham Hip Resurfacing completed the Veteran’s Rand 36 (VR-36), modified Harris Hip Score (mHHS), Tegner Activity Score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at two years and a minimum of three years. A change in score was assessed against minimal clinically important difference (MCID) and patient-acceptable symptom state (PASS) thresholds. Binary logistic regression was used to assess the relationship between patient factors and deterioration in PASS status between follow-ups. Results. Overall, 18% of patients reported reductions in mHHS total score exceeding MCID, and 21% reported similar reductions for WOMAC function scores. Nonetheless, almost all patients remained above PASS thresholds for WOMAC function (98%) and mHHS (93%). Overall, 66% of patients with mHHS scores < PASS at two years reported scores > PASS at latest follow-up. Conversely, 6% of patients deteriorated from > PASS to < PASS between follow-ups. Multivariable modelling indicated body mass index (BMI) > 27 kg/m. 2. , VR-36 Physical Component Score (PCS) < 51, VR-36 Mental Component Score (MCS) > 55, mHHS < 84 at two years, female sex, and bone graft use predicted these deteriorating patients with 79% accuracy and an area under the curve (AUC) of 0.84. Conclusion. Due to largely acceptable results at a later follow-up, extensive monitoring of multiple PROMs is not recommended for Birmingham Hip Resurfacing patients unless they report borderline or unacceptable hip function at two years, are female, are overweight, or received a bone graft during surgery. Cite this article: Bone Joint J 2019;101-B:1431–1437

Aims

Fungal periprosthetic joint infections (fPJIs) are rare complications, constituting only 1% of all PJIs. Neither a uniform definition for fPJI has been established, nor a standardized treatment regimen. Compared to bacterial PJI, there is little evidence for fPJI in the literature with divergent results. Hence, we implemented a novel treatment algorithm based on three-stage revision arthroplasty, with local and systemic antifungal therapy to optimize treatment for fPJI.

Aims. To our knowledge, no study has compared the long-term results of cemented and hybrid total hip arthroplasty (THA) in patients with osteoarthritis (OA) secondary to congenital hip disease (CHD). This is a demanding procedure that may require special techniques and implants. Our aim was to compare the long-term outcome of cemented low-friction arthroplasty (LFA) and hybrid THA performed by one surgeon. Patients and Methods. Between January 1989 and December 1997, 58 hips (44 patients; one man, 43 woman; mean age 56.6 years (25 to 77)) with OA secondary to CHD were treated with a cemented Charnley LFA (group A), and 55 hips (39 patients; two men, 37 women; mean age 49.1 years (27 to 70)) were treated with a hybrid THA (group B), by the senior author (GH). The clinical outcome and survivorship were compared. Results. At all timepoints, group A hips had slightly better survivorship than those in group B without a statistically significant difference, except for the 24-year survival of acetabular components with revision for aseptic loosening as the endpoint, which was slightly worse. The survivorship was only significantly better in group A compared with group B when considering reoperation for any indication as the endpoint, 15 years postoperatively (74% vs 52%, p = 0.018). Conclusion. We concluded that there was not a substantial difference at almost any time in the outcome of cemented Charnley LFAs compared with hybrid THAs when treating patients with OA of the hip secondary to CHD. We believe, however, that after improvements in the design of components used in hybrid THA, this could be the method of choice, as it is technically easier with a shorter operating time. Cite this article: Bone Joint J 2019;101-B:1050–1057

Aims. Few studies have examined the long-term outcome of carpal tunnel release (CTR). The aim of this study was to evaluate the patient-reported long-term outcome of CTR for electrophysiologically severe carpal tunnel syndrome (CTS). Patients and Methods. We reviewed the long-term outcome of 40 patients with bilateral severe CTS who underwent 80 CTRs (46 open, 34 endoscopic) between 2002 and 2012. The outcomes studied were patient-reported outcomes of numbness resolution, the Boston Carpal Tunnel Questionnaire (BCTQ) score, and patient satisfaction. Results. The mean follow-up was 9.3 years. Complete resolution of numbness was reported by 93.8% of patients, persistent numbness by 3.8%, and recurrent numbness by 2.5%. The mean BCTQ symptom score was 1.1 (. sd. 0.3; 1.0 to 2.55) and the mean Boston function score was 1.15 (. sd. 0.46; 1.0 to 3.5). 72.5% of patients were asymptomatic and had no functional impairment. Men had poorer outcomes than women and patients < 55 years had poorer outcomes than patients ≥ 55 years. All patients who had undergone endoscopic CTR reported complete resolution of numbness compared with 89.1% of those who had undergone open release (p = 0.047). There was no significant difference in outcome between dominant and non-dominant hands. Patient satisfaction rates were good. There were no adverse events. Conclusion. CTR has a favourable outcome and good rates of satisfaction, even in patients with bilateral severe CTS at a mean of nine years after surgery. Endoscopic CTR has a higher rate of numbness resolution than open surgery. There were no significant differences in outcome between the dominant and non-dominant hand. Cite this article: Bone Joint J 2017;99-B:1348–53

Aims. The aim of this study was to explore whether time to surgery affects functional outcome in displaced proximal humeral fractures. Methods. A total of 250 patients presenting within three weeks of sustaining a displaced proximal humeral fracture involving the surgical neck were recruited at 32 acute NHS hospitals in the United Kingdom between September 2008 and April 2011. Of the 125 participants, 109 received surgery (fracture fixation or humeral head replacement) as per randomization. Data were included for 101 and 67 participants at six-month and five-year follow-up, respectively. Oxford Shoulder Scores (OSS) collected at six, 12, and 24 months and at three, four, and five years following randomization was plotted against time to surgery. Long-term recovery was explored by plotting six-month scores against five-year scores and agreement was illustrated with a Bland-Altman plot. Results. The mean time from initial trauma to surgery was 10.5 days (1 to 33). Earlier surgical intervention did not improve OSS throughout follow-up, nor when stratified by participant age (< 65 years vs ≥ 65 years) and fracture severity (one- and two-part vs three- and four-part fractures). Participants managed later than reported international averages (three days in the United States and Germany, eight days in the United Kingdom) did not have worse outcomes. At five-year follow-up, 50 participants (76%) had the same or improved OSS compared with six months (six-month mean OSS 35.8 (SD 10.0); five-year mean OSS 40.1 (SD 9.1); r = 0.613). A Bland-Altman plot demonstrated a positive mean difference (3.3 OSS points (SD 7.92)) with wide 95% limits of agreement (-12.2 and 18.8 points). Conclusion. Timing of surgery did not affect OSS at any stage of follow-up, irrespective of age or fracture type. Most participants had maximum functional outcome at six months that was maintained at five years. These findings may help guide providers of trauma services on surgical prioritization. Cite this article: Bone Joint J 2020;102-B(1):33–41

Aims

To assess the effect of age on clinical outcome and revision rates in patients who underwent total ankle arthroplasty (TAA) for end-stage ankle osteoarthritis (OA).

Aims. The practice of alternating operating theatres has long been used to reduce surgeon idle time between cases. However, concerns have been raised as to the safety of this practice. We assessed the payments and outcomes of total knee arthroplasty (TKA) performed during overlapping and nonoverlapping days, also comparing the total number of the surgeon’s cases and the total time spent in the operating theatre per day. Materials and Methods. A retrospective analysis was performed on the Centers for Medicare & Medicaid Services (CMS) Limited Data Set (LDS) on all primary elective TKAs performed at the New England Baptist Hospital between January 2013 and June 2016. Using theatre records, episodes were categorized into days where a surgeon performed overlapping and nonoverlapping lists. Clinical outcomes, economic outcomes, and demographic factors were calculated. A regression model controlling for the patient-specific factors was used to compare groups. Total orthopaedic cases and aggregate time spent operating (time between skin incision and closure) were also compared. Results. A total of 3633 TKAs were performed (1782 on nonoverlapping days; 1851 on overlapping days). There were no differences between the two groups for length of inpatient stay, payments, mortality, emergency room visits, or readmission during the 90-day postoperative period. The overlapping group had 0.74 fewer skilled nursing days (95% confidence interval (CI) -0.26 to -1.22; p < 0.01), and 0.66 more home health visits (95% CI 0.14 to 1.18; p = 0.01) than the nonoverlapping group. On overlapping days, surgeons performed more cases per day (5.01 vs 3.76; p < 0.001) and spent more time operating (484.55 minutes vs 357.17 minutes; p < 0.001) than on nonoverlapping days. Conclusion. The study shows that the practice of alternating operating theatres for TKA has no adverse effect on the clinical outcome or economic utilization variables measured. Furthermore, there is opportunity to increase productivity with alternating theatres as surgeons with overlapping cases perform more cases and spend more time operating per day. Cite this article: Bone Joint J 2019;101-B:1081–1086

Objectives. A lack of connection between surgeons and patients in evaluating the outcome of total knee arthroplasty (TKA) has led to the search for the ideal patient-reported outcome measure (PROM) to evaluate these procedures. We hypothesised that the desired psychometric properties of the ideal outcome tool have not been uniformly addressed in studies describing TKA PROMS. Methods. A systematic review was conducted investigating one or more facets of patient-reported scores for measuring primary TKA outcome. Studies were analysed by study design, subject demographics, surgical technique, and follow-up adequacy, with the ‘gold standard’ of psychometric properties being systematic development, validity, reliability, and responsiveness. Results. A total of 38 articles reported outcomes from 47 different PROMS to 85 541 subjects at 26.3 months (standard deviation 30.8) post-operatively. Of the 38, eight developed new scores, 20 evaluated existing scores, and ten were cross-cultural adaptation of existing scores. Only six of 38 surveyed studies acknowledged all ‘gold standard’ psychometric properties. The most commonly studied PROMS were the Oxford Knee Score, New Knee Society Score, Osteoarthritis Outcome Score, and Western Ontario and McMaster Universities Osteoarthritis Index. Conclusions. A single, validated, reliable, and responsive PROM addressing TKA patients’ priorities has not yet been identified. Moreover, a clear definition of a successful procedure remains elusive. Cite this article: Bone Joint Res 2015;4:120–127

Aims. The aim of this study was to compare patient-reported outcome measures (PROMs) and the Single Assessment Numerical Evaluation (SANE) score in patients treated with a volar locking plate for a distal radial fracture. Methods. This study was a retrospective review of a prospective database of 155 patients who underwent internal fixation with a volar locking plate for a distal radial fracture between August 2014 and April 2017. Data which were collected included postoperative PROMs (Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) and Patient-Rated Wrist Evaluation (PRWE)), and SANE scores at one month (n = 153), two months (n = 155), three months (n = 144), six months (n = 128), and one year (n = 73) after operation. Patients with incomplete data were excluded from this study. Correlation and agreement between PROMs and SANE scores were evaluated. Subgroup analyses were carried out to identify correlations according to variables such as age, the length of follow-up, and subcategories of the PRWE score. Results. The Pearson correlation coefficient (r) between PROMs and SANE scores was -0.76 (p < 0.001) for DASH and -0.72 (p < 0.001) for PRWE, respectively. Limits of agreement between PROMs and ‘100-SANE’ scores were met for at least 93% of the data points. In subgroup analysis, there were significant negative correlations between PROMs and SANE scores for all age groups and for follow-up of more than six months. The correlation coefficient between PRWE subcategories and SANE score was -0.67 (p < 0.001) for PRWE pain score and -0.69 (p < 0.001) for PRWE function score, respectively. Conclusion. We found a significant correlation between postoperative SANE and PROMs in patients treated with a volar locking plate for a distal radial fracture. The SANE score is thus a reliable indicator of outcome for patients who undergo surgical treatment for a radial fracture. Cite this article: Bone Joint J 2020;102-B(6):744–748

Aims. The aim of this study was to record the incidence of post-traumatic osteoarthritis (OA), the need for total hip arthroplasty (THA), and patient-reported outcome measures (PROMS) after surgery for a fracture of the acetabulum, in our centre. Patients and Methods. All patients who underwent surgery for an acetabular fracture between 2004 and 2014 were included. Patients completed the 36-Item Short Form Health Survey (SF-36) and the modified Harris Hip Score (mHHS) questionnaires. A retrospective chart and radiographic review was performed on all patients. CT scans were used to assess the classification of the fracture and the quality of reduction. Results. A total of 220 patients were included, of which 55 (25%) developed post-traumatic OA and 33 (15%) underwent THA. A total of 164 patients completed both questionnaires. At a mean follow-up of six years (2 to 10), the mean SF-36 score for patients with a preserved hip joint was higher on role limitations due to physical health problems than for those with OA or those who underwent THA. In the dimension of bodily pain, patients with OA had a significantly better score than those who underwent THA. Patients with a preserved hip joint had a significantly better score on the function scale of the mHHS and a better total score than those with OA or who underwent THA. Conclusion. Of the patients who were treated surgically for an acetabular fracture (with a mean follow-up of six years), 15% underwent THA at a mean of 2.75 years postoperatively. Patients with a THA had a worse functional outcome than those who retain their native hip joint. We recommend using PROMS and CT scans when reviewing these patients. Cite this article: Bone Joint J 2018;100-B:640–5

Aims. The aims of this study were to describe the course of non-operatively managed, bilateral Perthes’ disease, and to determine specific prognostic factors for the radiographic and clinical outcome. . Patients and Methods. We identified 40 children with a mean age of 5.9 years (1.8 to 13.5), who were managed non-operatively for bilateral Perthes’ disease from our prospective, multicentre study of this condition, which included all children in Norway who were diagnosed with Perthes’ disease in the five-year period between 1996 and 2000. All children were followed up for five years. . The hips were classified according to the Catterall classification. A modified three-group Stulberg classification was used as an outcome measure, with a spherical femoral head being defined as a good outcome, an oval head as fair, and a flat femoral head as a poor outcome. . Results. Concurrent, simultaneous bilateral Perthes’ disease was seen in 23 children and 17 had the sequential onset of bilateral disease. The mean delay in onset for the second hip in the latter group was 1.9 years (0.3 to 5.5). . The five-year radiographic outcome was good in 30 (39%), fair in 25 (33%) and poor in 21 (28%) of the hips. The strongest predictors of poor outcome were > 50% necrosis of the femoral head, with odds ratio (OR) 19.6, and age at diagnosis > 6 years (OR 3.3). Other risk factors for poor outcome were the timing of the onset of disease, where children with the sequential onset of bilateral disease had a higher risk than those with the concurrent onset of bilateral disease (p = 0.021, chi-squared test). . Following a diagnosis of Perthes’ disease in one hip, there was a 5% chance of developing it in the contralateral hip. . Conclusion. These results imply that we need to distinguish between children with concurrent onset and those with sequential onset of bilateral Perthes’ disease, as the outcomes may be different. This has not been previously described. Children with concurrent onset of bilateral disease had a similar outcome to our previous series of those with unilateral disease, whereas children with sequential onset of bilateral disease had a worse prognosis. The increased risk of developing Perthes’ disease in the contralateral hip in those with unilateral disease is important information for the child and parents. . Cite this article: Bone Joint J 2016;98-B:569–75