Periprosthetic osseointegration fractures are infrequent and management is familiar.

AIMS: Osseointegrated prosthetic limbs allow better mobility than socket-mounted prosthetics for lower limb amputees. Fractures, however, can occur in the residual limb, but they have rarely been reported. Approximately 2% to 3% of amputees with socket-mounted prostheses may fracture within five years. This is the first study which directly addresses the risks and management of periprosthetic osseointegration fractures in amputees. METHODS: A retrospective review identified 518 osseointegration procedures which were undertaken in 458 patients between 2010 and 2018 for whom complete medical records were available. Potential risk factors including time since amputation, age at osseointegration, bone density, weight, uni/bilateral implantation and sex were evaluated with multiple logistic regression. The mechanism of injury, technique and implant that was used for fixation of the fracture, pre-osseointegration and post fracture mobility (assessed using the K-level) and the time that the prosthesis was worn for in hours/day were also assessed. RESULTS: There were 22 periprosthetic fractures; they occurred exclusively in the femur: two in the femoral neck, 14 intertrochanteric and six subtrochanteric, representing 4.2% of 518 osseointegration operations and 6.3% of 347 femoral implants. The vast majority (19/22, 86.4%) occurred within 2 cm of the proximal tip of the implant and after a fall. No fractures occurred spontaneously. Fixation most commonly involved dynamic hip screws (10) and reconstruction plates (9). No osseointegration implants required removal, the K-level was not reduced after fixation of the fracture in any patient, and all retained a K-level of ≥ 2. All fractures united, 21 out of 22 patients (95.5%) wear their osseointegration-mounted prosthetic limb longer daily than when using a socket, with 18 out of 22 (81.8%) reporting using it for ≥ 16 hours daily. Regression analysis identified a 3.89-fold increased risk of fracture for females (p = 0.007) and a 1.02-fold increased risk of fracture per kg above a mean of 80.4 kg (p = 0.046). No increased risk was identified for bilateral implants (p = 0.083), time from amputation to osseointegration (p = 0.974), age at osseointegration (p = 0.331), or bone density (g/cm2, p = 0.560; T-score, p = 0.247; Z-score, p = 0.312). CONCLUSION: The risks and sequelae of periprosthetic fracture after press-fit osseointegration for amputation should not deter patients or clinicians from considering this procedure. Females and heavier patients are likely to have an increased risk of fracture. Age, years since amputation, and bone density do not appear influential. Cite this article: Bone Joint J 2020;102-B(2):162-169.

Fixed flexion deformity following total knee arthroplasty. A prospective study of the natural history.

INTRODUCTION: Stiffness following total knee arthroplasty (TKA) is a disabling problem resulting in pain and reduced function. OBJECTIVE: The aim of our study was to evaluate the natural course of fixed flexion deformity (FFD ) following primary total knee arthroplasty. METHODS: Prospective review of 1626 patients undergoing primary TKA from 2001 to 2006 with a minimum of 4 year follow up. Demographic data included post-operative range of motion; type of prosthesis used, treatment modalities for stiffness and the final range of motion were recorded. FFD was defined as class 1(5-15 degrees) and Class 2 (> 15 degrees). Patients with a pre-operative FFD of >15, infection, stiffness treated with manipulation or revision surgery were excluded from the study. RESULTS: Of the 1626 patients evaluated, 170 (10.5%) presented with a FFD. 18 patients were excluded from the study and 16 were lost to follow up. 124 (91.2%) were class 1 and 12 (8.8%) were class 2. FFD improved from a mean of 8.8 degrees to 0.4 degrees (p<0.0001) in 11.4 months. In 94.1% patients the FFD completely resolved (i.e. < 5 degrees) at a mean of 10.8 months (p<0.0001). In the remaining 5.9% of patients, FFD improved from a mean of 16.4 to 6.9 degrees at a mean follow up of 21.5 months (p<0.0001). CONCLUSION: A gradual improvement in the FFD can be expected up to 2 years and a small residual flexion contracture does not cause functional deficit. LEVEL OF EVIDENCE: Prospective cohort study, level 3.

Reverse obliquity and transverse fractures of the trochanteric region of the femur; a review of 101 cases.

BACKGROUND: Reverse obliquity and transverse fractures of the proximal femur represent a distinct fracture pattern in which the mechanical forces displace the femur medially thus increasing the risk of fixation failure. There is a paucity of published literature in this area of trauma. This study constitutes the largest series of such fractures. METHODS: Using a retrospective analysis of prospectively collected data from a single institution, 101 reverse obliquity and transverse fracture patterns were identified from 3336 consecutive hip fractures. All surviving patients were followed up for 1 year. RESULTS: Of 100 patients treated operatively, 59 were treated with 135 degrees sliding hip screws (SHS), 19 with a Medoff plates modification of the SHS, three with a sliding hip screw and trochanteric stabilising plate and 19 with intramedullary sliding hip screw devices. Nine fracture fixation-healing complications occurred, with cut-out being the commonest complication (seven cases). Cut-out of the implant was associated with femoral medialisation and a larger tip to apex distance. CONCLUSION: This fracture pattern is a challenge for the orthopaedic surgeon with a high risk of fracture healing complications. The 135 degrees SHS and the intramedullary devices had similar failure rates.