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Background: The use of a single dose of intra-articular antibiotic (IAA) has been reported in reducing the rate of prosthetic joint injection after total hip and knee arthroplasty. We examine the safety of IAA in primary hip and knee replacement surgery and the blood levels and joint fluid levels of vancomycin utilising this technique. Methods: From August to October 2021, 68 patients undergoing primary total joint arthroplasty (THA & TKA) were given 1g vancomycin intra-articularly (IA)after closure of the fascia. All patients received 2g cefazolin intravenously (IV) 30 min prior to the procedure as is our standard prophylaxis, and 21 of the patients (IA + IV) were also administered an additional 1 gm vancomycin IV. Post-operative blood vancomycin, creatinine land eGFR level monitoring was performed d1 and d3. To determine the post-operative intra-articular vancomycin levels, surgical drain fluid was sampled at day 1 and 2, in 10 patients. Results: All patients had serum vancomycin levels measured on day 1 and 3. In the group where vancomycin was injected after fascial closure, the average blood vancomycin level day 1 was 5.2 µg/ml (range 2.0-10.9) and day 3 was <1.4 µg/ml. The average pre-op creatinine levels were 69.4 µmol/L (56.1-82.6) compared to 70.2 µmol/L (57.0-83.4) on day 1 and 66.1 µmol/L (52.6-79.6) on day 3, (p = 0.663). The average pre-op eGFR levels (ml/min/1.73 m2) were 82.2 (76.0-88.3) compared to 81.7 (75.6-87.8) on day 1 and 83.0 (76.8-89.2) on day 3 (p = 0.736). Samples of joint fluid aspirated from surgical drains on day 1 and day 2 showed average vancomycin levels of 224 µg/ml and 51 µg/ml respectively, significantly higher than the MIC for Staph aureus. Conclusions: The use of intra-articular vancomycin is safe in primary TJA, with no renal damage and delivers levels within the joint which are highly therapeutic for at least 48 h post injection.

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PURPOSE: Patellar dislocation is associated with a range of anatomical abnormalities affecting the trochlea, extensor mechanism and the tibia. The relationship between patellofemoral instability and rotational abnormalities of the posterior condyles, trochlear groove and proximal tibia has not been adequately determined. This study aimed to identify the frequency and severity of anatomical risk factors to determine their relative contribution to patellofemoral instability. METHODS: A retrospective morphological study was undertaken comparing multiple anatomical measurements with magnetic resonance imaging of 50 patients with patellofemoral instability to an age- and gender-matched Control group (n = 50). Several techniques were assessed measuring both femoral and tibial axial asymmetry. A new measurement, tibial rotational asymmetry, comparing a line between the midpoints of the collateral ligaments to the axis between the patellar tendon and posterior cruciate ligament, was assessed for its association with patellofemoral instability. RESULTS: Compared to the controls, the patellofemoral instability group demonstrated a significant difference in tibial rotational asymmetry, with a mean of 2.9° (SD 3.2°) externally rotated vs - 1.6° (SD 2.2°) in the control group. Significant differences were also demonstrated regarding the sulcus angle, tibial tubercle-trochlear groove distance, tibial tubercle-posterior cruciate ligament distance, patellar size and the Insall-Salvati ratio. There were no differences between groups regarding the lengths of the posterior condyles, the heights of the trochlear ridges or lateralisation of the trochlear groove. Further analysis of the patellofemoral instability group revealed a subgroup of males with normal anatomy (7/50) and a subgroup of females with isolated patella alta (7/50). CONCLUSION: Patellofemoral instability is associated with tibial rotational asymmetry due to lateralisation of the tibial tubercle. It is also associated with patella alta and reduced trochlear groove depth. The femoral axial shape is otherwise unchanged. LEVEL OF EVIDENCE: III.

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As the numbers of arthroplasties performed worldwide increase, so do complications such as prosthetic joint infection. Cases that require a two-stage revision of a total femur replacement in the femur pose an ongoing challenge to the modern orthopedic surgeon. Unlike antibiotic spacers in hip and knee arthroplasty, there lacks a commercially available cement spacer for use in total femur replacements. We describe a novel technique for the intraoperative fabrication of a total femur spacer which uses modular components. As such, our technique is unique as it is modular and, therefore, highly customisable to each individual patient. Individual components can be made by different members of the team simultaneously and then assembled to make the final construct, thereby minimizing operative time. Furthermore, the inherent stability of the spacer allows immediate partial weightbearing and functional rehabilitation while patients are waiting for their second-stage procedure.

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STUDY DESIGN: Meta-analysis and systematic review of literature. OBJECTIVE: In the late 1990s, spinal surgeons experimented by using maxillofacial fixation plates as an alternative to sutures, anchors, and local spinous process autografts to provide a more rigid and lasting fixation for laminoplasty. This eventually led to the advent of laminoplasty mini-plates, which are currently used. The objective is to compare laminoplasty techniques with plate and without plate with regard to functional outcome results. METHODS: Qualitative and quantitative analyses were performed to evaluate the currently available studies in an attempt to justify the use of a plate in laminoplasty. RESULTS: The principal finding of this study was that there was no statistically significant difference in clinical outcome between the 2 different techniques of laminoplasty. CONCLUSION: There is not enough evidence in the literature to support one technique over the other, and hence, there is no evidence to support change in practice (using or not using the plate in laminoplasty). A randomized controlled trial will give a better comparison between the 2 groups.

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BACKGROUND: Femoral component malrotation is a common cause of patient dissatisfaction after total knee arthroplasty. The sulcus line (SL) is more accurate than Whiteside's line as it corrects for variation in the coronal orientation of the groove. The hypothesis is that averaging the SL and posterior condylar axis (PCA) will reduce femoral malrotation. METHODS: The component was inserted at a position between the SL and PCA in 91 patients. An intraoperative photograph was taken showing the landmarks. These were compared to the component position achieved relative to the surgical epicondylar axis (SEA) on a postoperative CT scan. The component position was compared to the position achieved using the individual landmarks. RESULTS: Relative to the SEA, the final component position was 0.6° (SD 1.4°, range -3.8° to +4.0°), the coronally corrected SL position was -0.7° (SD 2.3°, -5.5° to +4.6°), the PCA position was 0.9° (SD 1.9°, -6.1° to +5.0°). Averaging the landmarks significantly decreased the variance of the component position compared to using the SL and PCA individually. The number of outliers (>3° from SEA) was also significantly less (p < 0.05) for the average position (2/84) when each was compared to the SL (16/84) and PCA (14/84) individually. In 21/84 (25%) of cases, there was more than 4° of divergence between the SL and PCA. CONCLUSIONS: Averaging the SL and the PCA decreases femoral component malrotation. Femora are frequently asymmetrical in the axial plane. Referencing posterior condyles alone to set rotation is likely to cause high rates of patellofemoral malalignment.

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PURPOSE: This study was aimed to highlight neck notching as a potential cause of failure in modular neck total hip arthroplasty. It aimed to identify both the combination of modular components that place patients at greatest risk of failure and the potential mechanism for failure. METHODS: This study involved a retrospective review of 301 total hip arthroplasties (THA) using Kinectiv modular neck Technology (Zimmer, Warsaw, Indiana). The primary outcome was the presence of neck notching requiring revision. Patient records, operative notes and postoperative radiographs were reviewed. A statistical analysis was performed. RESULTS: A total of 301 THA were performed on 290 patients. There were 7 failures (2.3%). All 7 failures involved a modular combination of an anteverted neck, extended offset and length code -8 (failure rate of 36.8%, p<0.001). CONCLUSIONS: We identified femoral neck notching as a potential cause of failure in modular neck THA. The combination of an anteverted neck, extended offset and length code -8 was associated with a high rate of neck notching using the Kinectiv modular neck Technology (Zimmer, Warsaw, Indiana). Based on our experience with this prosthesis we advise caution when using this particular combination of implants.

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