No radiographic difference between patient-specific guiding and conventional Oxford UKA surgery

Implant position is an important factor in unicompartmental knee arthroplasty (UKA) surgery. Results on conventional UKA alignment are commonly described in literature. Patient-specific guiding (PSG) is a new technique for positioning the Oxford UKA. Our hypothesis is that PSG improves component position without affecting the HKA angle.This prospective study compares the results of our first thirty cases of cementless Oxford UKA using PSG with thirty cases using conventional outlining. Baseline characteristics for both groups were identical. Details on handling of the guide, estimated blood loss and operation time were recorded. Postoperative screened radiographs and standing long-leg radiographs of both groups were compared.Median AP position of the femoral component was 3 degrees varus (-5 to 9) using PSG versus 2 degrees varus (-10 to 8) for the conventional group. For the femoral flexion, this was 9 degrees flexion (0-16) using PSG versus 12 degrees flexion (0-20). The tibial median AP position was 1 degree varus (-3 to 7) using PSG versus 2 degrees varus (-5 to 10). The median tibial posterior slope was 5 degrees (1-10) using PSG versus 5 degrees (0-12). All guides aligned well. No conversion to conventional outlining was performed, and no significant changes had to be made to the original approved plan. Operation time, estimated blood loss and postoperative haemoglobin drop were not significantly different between both groups.Implant position was not different between both groups, even in the early phase of the learning curve. Perioperative results were not different between both groups.III

Patient-specific positioning guides for total knee arthroplasty: no significant difference between final component alignment and pre-operative digital plan except for tibial rotation

To assess whether there is a significant difference between the alignment of the individual femoral and tibial components (in the frontal, sagittal and horizontal planes) as calculated pre-operatively (digital plan) and the actually achieved alignment in vivo obtained with the use of patient-specific positioning guides (PSPGs) for TKA. It was hypothesised that there would be no difference between post-op implant position and pre-op digital plan.Twenty-six patients were included in this non-inferiority trial. Software permitted matching of the pre-operative MRI scan (and therefore calculated prosthesis position) to a pre-operative CT scan and then to a post-operative full-leg CT scan to determine deviations from pre-op planning in all three anatomical planes.For the femoral component, mean absolute deviations from planning were 1.8A degrees (SD 1.3), 2.5A degrees (SD 1.6) and 1.6A degrees (SD 1.4) in the frontal, sagittal and transverse planes, respectively. For the tibial component, mean absolute deviations from planning were 1.7A degrees (SD 1.2), 1.7A degrees (SD 1.5) and 3.2A degrees (SD 3.6) in the frontal, sagittal and transverse planes, respectively. Absolute mean deviation from planned mechanical axis was 1.9A degrees. The a priori specified null hypothesis for equivalence testing: the difference from planning is > 3 or <-3 was rejected for all comparisons except for the tibial transverse plane.PSPG was able to adequately reproduce the pre-op plan in all planes, except for the tibial rotation in the transverse plane. Possible explanations for outliers are discussed and highlight the importance for adequate training surgeons before they start using PSPG in their day-by-day practise.Prospective cohort study, Level II

Is minimally invasive surgery less invasive in total hip replacement? A pilot study

It has been suggested that minimally invasive surgery (MIS) in total hip replacement (THR) is less traumatic than standard techniques. This study was designed to address the question of whether an anterior MIS approach generates less inflammation and muscle damage than the standard posterolateral (PL) approach. Inflammation parameters such as interleukin-6 (IL-6), muscle damage parameters like heart type fatty acid binding protein (H-FABP), and haemoglobin (Hb) levels were determined pre-operatively and at five consecutive points post-operatively in 10 patients operated through a MIS anterior approach and in 10 patients operated through a PL approach. The mean IL-6 concentration increased from 3 pg/ml in both groups pre-operatively to 78.5 pg/ml (PL group) vs 74.8 pg/ml (MIS group) at 6 hours post-operatively and reached a maximum of 100 pg/ml (PL group) vs 90.5 pg/ml pg/ml (MIS group) after 24 hours. Up to this time point, there was a decrease in both groups. The post-operative mean H-FABP concentration increased to 10.7mug/l in the PL group vs 15.8 mug/l in the MIS group. It formed a plateau and decreased after 24 hours post-operatively. The Hb levels were 14.5 g/dl before surgery and decreased to 10.7 g/dl (PL group) and 10.0 g/dl (MIS group) at 72 hours post-operatively. No significant differences were found between the two approaches either in inflammation and muscle damage or blood loss. Although the absence of a learning curve may explain the lack of a difference between both techniques, we speculate that the term MIS is at least doubtful in terms of being less traumatic

Patient-specific instruments do not show advantage over conventional instruments in unicompartmental knee arthroplasty at 2 year follow-up: a prospective, two-centre, randomised, double-blind, controlled trial

Purpose The aim of this two-centre RCT was to compare pre- and post-operative radiological, clinical and functional outcomes between patient-specific instrumentation (PSI) and conventional instrumented (CI) unicompartmental knee arthroplasty (UKA). It was hypothesised that both alignment methods would have comparable post-operative radiological, clinical and functional outcomes.Methods One hundred and twenty patients were included, and randomly allocated to the PSI or the CI group. Outcome measures were peri-operative outcomes (operation time, length of hospital stay and intra-operative changes of implant size) and post-operative radiological outcomes including the alignment of the tibial and femoral component in the sagittal and frontal plane and the hip-knee-ankle-axis (HKA-axis), rate of adverse events (AEs) and patient-reported outcome measures (PROMs) pre-operatively and at 3, 12 and 24 months post-operatively.Results There was a statistically significant difference (p < 0.05) in alignment of the femoral component in the frontal plane in favour of the CI method. No statistically significant differences were found for the peri-operative data or in the functional outcome at 2-year follow-up. In the PSI group, the approved implant size of the femoral component was correct in 98.2% of the cases and the tibial component was correct in 60.7% of the cases. There was a comparable rate of AEs: 5.1% in the CI and 5.4% in the PSI group.Conclusion The PSI method did not show an advantage over CI in regard of positioning of the components, nor did it show an improvement in clinical or functional outcome. We conclude that the possible advantages of PSI do not outweigh the costs of the MRI scan and the manufacturing of the PSI