Total elbow arthroplasty (TEA) usage is increasing owing to expanded surgical indications, better implant designs, and improved long-term survival. Correct humeral implant positioning has been shown to diminish stem loading in vitro, and radiographic loosening in in the long-term. Replication of the native elbow centre of rotation is thought to restore normal muscle moment arms and has been suggested to improve elbow strength and function. While much of the focus has been on humeral component positioning, little is known about the effect of positioning of the ulnar stem on post-operative range of motion and clinical outcomes. The purpose of this study is to determine the effect of the sagittal alignment and positioning of the humeral and ulnar components on the functional outcomes after TEA.

Between 2003 and 2016, 173 semi-constrained TEAs (Wright-Tornier Latitude/Latitude EV, Memphis, TN, USA) were performed at our institution, and our preliminary analysis includes 46 elbows in 41 patients (39 female, 7 male). Patients were excluded if they had severe elbow deformity precluding reliable measurement, experienced a major complication related to an ipsilateral upper limb procedure, or underwent revision TEA. For each elbow, saggital alignment was compared pre- and post-operatively. A best fit circle of the trochlea and capitellum was drawn, with its centre representing the rotation axis. Ninety degree tangent lines from the intramedullary axes of the ulna and humerus, and from the olecranon tip to the centre of rotation were drawn and measured relative to the rotation axis, representing the ulna posterior offset, humerus offset, and ulna proximal offset, respectively. In addition, we measured the ulna stem angle (angle subtended by the implant and the intramedullary axis of the ulna), as well as radial neck offset (the length of a 90o tangent line from the intramedullary axis of the radial neck and the centre of rotation) in patients with retained or replaced radial heads. Our primary outcome measure was the quickDASH score recorded at the latest follow-up for each patient. Our secondary outcome measures were postoperative flexion, extension, pronation and supination measured at the same timepoints. Each variable was tested for linear correlation with the primary and secondary outcome measures using the Pearson two-tailed test.

At an average follow-up of 6.8 years (range 2–14 years), there was a strong positive correlation between anterior radial neck offset and the quickDASH (r=0.60, p=0.001). There was also a weak negative correlation between the posterior offset of the ulnar component and the qDASH (r=0.39, p=0.031), and a moderate positive correlation between the change in humeral offset and elbow supination (r=0.41, p=0.044). The ulna proximal offset and ulna stem angle were not correlated with either the primary, or secondary outcome measures.

When performing primary TEA with radial head retention, or replacement, care should be taken to ensure that the ulnar component is correctly positioned such that intramedullary axis of the radial neck lines up with the centre of elbow rotation, as this strongly correlates with better function and less pain after surgery.

Infection after Total Knee arthroplasty is devastating. The primary aim of this study was to characterise deep prosthesis infection in patients presenting greater than 3 months from index surgery. A retrospective single centre case control study of 1641 primary knee arthroplasties conducted between 1998 and 2006. All infected patients were identified (n=35) and those occurring within 3 months of surgery (n = 12) were excluded. All remaining infections (n=23) were classified into “latent” and “haematogenous”. Latent infections (n=7) were classified as having symptoms persisting from the time of surgery. Haematogenous infections (n=16) were those with an uneventful recovery and then a sudden onset of symptoms immediately prior to diagnosis of deep prosthetic infection. Each haematogenous infection was matched with 2 controls. Statistical analysis was performed between controls and the 16 haematogenous infections to determine any differences.

The overall prosthetic infection rate was 2.13%. Early infections accounted for 0.73% of the total and “haematogenous” infections for 0.98% of the total. The median time to infection in the “haematogenous” group was 1.6 years (Range 103 to 1803 days) and the median follow up time was 3.3 years (Range 230–3410). 94% (n=15) of the “haematogenous” group described a sentinel event prior to infection compared with 66% (n=21) of patients in the control group who reported an event with no subsequent progression to infection (P=0.04). Common preceding events included traumatic haemarthrosis in 31%, distant infections (eg dental abscess, intrathecal pump site infection, infected permacath, sternal wound infection, UTI) in 31% and cellulitis in 19%. The most common infecting organism was staphylococcus aureus in 56.5% (2 MRSA, 11 MSSA). Significant risk factors included the presence of diabetes (P=0.042), obesity and diabetes (P=0.044) and the number of co-morbidities (P=0.07). Infections were managed with debridement and washout (n=9) or removal of the implant with or without revision (n=7).

A significant number of patients who develop haematogenous infection have a preceding sentinel event. Haematogenous infections are more likely to occur in patients with diabetes or those with multiple co-morbidities. This group should be counseled regarding the ongoing risk of deep prosthetic infection.