Kinematics of a bicruciate-retaining total knee arthroplasty.

PURPOSE: The recently reintroduced bicruciate-retaining Total Knee Arthroplasty (BCR TKA) is an interesting approach in the quest for close replication of knee joint biomechanics and kinematics closer to the native knee. Therefore, this study aimed at providing a detailed biomechanical view on the functional resemblance of BCR TKA to the native knee joint. METHODS: Seven fresh-frozen full leg cadaver specimens (76 ± 10 year) were mounted in a 6 degrees-of-freedom kinematic rig that applied a dynamic squatting motion knee flexion. Two motion patterns were performed pre- and post-implantation of a fixed bearing BCR TKA: passive flexion-extension and squatting while an infrared camera system tracked the location of reflective markers attached to the tibia and femur. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests in triplicate. RESULTS: Overall, differences in tibiofemoral kinematics between native knee and BCR TKA were small. Some minor differences appeared under the load of a squat: less internal tibial rotation and some minor paradoxical anterior translation of the medial femoral condyle during mid-flexion. BCR TKA may slightly elevate the joint line. Knee laxity as measured by the Lachman and varus/valgus tests was not significantly influenced by BCR TKA implantation. CONCLUSION: As both cruciate ligaments are preserved with BCR TKA the unloaded knee closely resembles native knee kinematics including preserving the rollback mechanism. The loss of the conforming anatomy of menisci and tibial cartilage and replacement via a relatively flat polyethylene inlay may account for the loss of tibial internal rotation and the slight paradoxical AP motion of the medial femoral condyle with BCR TKA. This phenomenon reproduces findings made earlier with fixed bearing unicondylar knee arthroplasty.

Acute and chronic coronoid reconstruction using the olecranon Tip.

Post-traumatic coronoid deficiency in the elbow can lead to chronic pain, instability and arthritis. A variety of osteochondral grafts have been used to reconstruct the coronoid, and restore elbow stability. The radial head and iliac crest grafts are the most common in the literature but have limitations. The olecranon tip is a promising alternative, with both cadaveric and computer models demonstrating superior congruency, without compromising elbow stability or disrupting the extensor mechanism. We present a small, case series demonstrating the technique for contralateral and ipsilateral grafts in both the acute and chronic setting.

Hemiarthroplasty versus open reduction internal fixation for intra-articular distal humerus fractures in older patients.

Background: Intra-articular distal humerus fractures in the older population remain a challenge to fix, due to the comminution of fragments and poor bone stock. Recently Elbow Hemiarthroplasty (EHA) has gained popularity to treat these fractures, however no studies exist comparing EHA to Open Reduction Internal Fixation (ORIF). Objectives: To compare the clinical outcomes of patients over the age of 60 years treated with ORIF or EHA for multi-fragmentary distal humerus fractures. Methods: Thirty-six patients (mean age 73 years) treated surgically for a multi-fragmentary intra-articular distal humeral fracture were followed up for a mean duration of thirty-four months (12-73 months). Eighteen patients were treated with ORIF and eighteen with EHA. The groups were matched for fracture type, demographic characteristics and follow up time. Outcome measures collected included Oxford Elbow Score (OES), Visual Analogue pain Score (VAS), range of motion (ROM), complications, re-operations and radiographic outcomes. The quality of ORIF was judged against set radiographic criteria in order to understand the effect of sub-optimal ORIF technique. Results: No significant clinical difference was found between EHA and ORIF in mean OES (42.5 vs 39.6, p = 0.28), mean VAS (0.5 vs 1.7, p = 0.08) or mean flexion-extension arc (123° vs 112°, p = 0.12). There were significantly more complications associated with ORIF compared to EHA (39% vs 6%, p = 0.04). ORIF executed with satisfactory fixation technique had a comparable complication rate compared to EHA (17% vs 6%, p = 0.6). Two ORIF patients required revision to Total Elbow Arthroplasty (TEA). None of the EHA patients required revision surgery. Conclusion: This study demonstrated similar short-term functional outcomes between EHA and ORIF for the treatment of multi-fragmentary intra-articular distal humeral fractures in patients >60 years of age. Early complications and re-operations were higher in the ORIF group, although this could be related to improper ORIF technique and patient selection.

Pre-operative arthritic glenoid assessment: 3D automated planning software versus manual multiplanar measurements of version and inclination.

Background: Preoperative CT-based planning is established in shoulder arthroplasty surgery. Automated planning software has become available to assist the surgeon and may increase reliability and efficiency. This study aims to evaluate the reliability of an automated 3-dimensional (3D) planning software package (Blueprint™ v2.1.5, Wright Medical Ltd) in the assessment of the arthritic shoulder against manual multiplanar measurement (MM). Methods: 74 CT studies acquired for preoperative shoulder arthroplasty planning were reviewed on two occasions by four different evaluators, taking manual measurement (MM) of glenoid version and inclination adjusted with multiplanar reformation and adhering to modified Freidman and Maurier methods. 15 scans were not processed by Blueprint due to incompatible scanning protocols or severe scapular dysmorphia. 59 Blueprint measures were compared with the manual data. Results: Version: Intra-observer reliability of glenoid version MM was excellent (mean ICC 0.92). Inter-observer reliability between all four readers was good (ICC 0.89). A Bland-Altman analysis of Blueprint versus MM for version measurements demonstrated a mean pair difference of -5.77 (95% CI -7.25 to 4.29). Inclination: Intra-rater and inter-rater reliabilities were good (ICC 0.85 and 0.80 respectively). Blueprint and MM values for inclination followed a more convergent pattern than for version. Bland-Altman analysis for inclination did not show substantial bias, with a mean pair difference of 1.4 (95% CI -0.1 to 2.9). Conclusion: Manual preoperative planning for shoulder arthroplasty is time consuming and requires experience. Automated 3D planning offers a consistent tool to assist the surgeon, notwithstanding intra-operative anatomical and technical variation, and margin of error. Surgeons should as ever be mindful of the specifics of a given automated program and our data quantified a bias for retroversion which may be important for measures close to the thresholds for augmentation or customised implants.

Challenging the mechanism of distal biceps tendon rupture using a video analysis study.

AIMS: The conventionally described mechanism of distal biceps tendon rupture (DBTR) is of a 'considerable extension force suddenly applied to a resisting, actively flexed forearm'. This has been commonly paraphrased as an 'eccentric contracture to a flexed elbow'. Both definitions have been frequently used in the literature with little objective analysis or citation. The aim of the present study was to use video footage of real time distal biceps ruptures to revisit and objectively define the mechanism of injury. METHODS: An online search identified 61 videos reporting a DBTR. Videos were independently reviewed by three surgeons to assess forearm rotation, elbow flexion, shoulder position, and type of muscle contraction being exerted at the time of rupture. Prospective data on mechanism of injury and arm position was also collected concurrently for 22 consecutive patients diagnosed with an acute DBTR in order to corroborate the video analysis. RESULTS: Four videos were excluded, leaving 57 for final analysis. Mechanisms of injury included deadlift, bicep curls, calisthenics, arm wrestling, heavy lifting, and boxing. In all, 98% of ruptures occurred with the arm in supination and 89% occurred at 0° to 10° of elbow flexion. Regarding muscle activity, 88% occurred during isometric contraction, 7% during eccentric contraction, and 5% during concentric contraction. Interobserver correlation scores were calculated as 0.66 to 0.89 using the free-marginal Fleiss Kappa tool. The prospectively collected patient data was consistent with the video analysis, with 82% of injuries occurring in supination and 95% in relative elbow extension. CONCLUSION: Contrary to the classically described injury mechanism, in this study the usual arm position during DBTR was forearm supination and elbow extension, and the muscle contraction was typically isometric. This was demonstrated for both video analysis and 'real' patients across a range of activities leading to rupture.Cite this article: Bone Jt Open 2022;3(10):826-831.

Current concepts in distal humeral hemiarthroplasty.

Multi-fragmentary intra-articular fractures of the distal humerus remain a challenge for both patients and surgeons. Open Reduction internal fixation remains the gold standard, however in older patients with comminuted fractures this might not be feasible. There is a growing interest in hemi-arthroplasty as a solution for these cases. However the current experience and follow-up in limited. This review article intends to describe the current concepts in elbow hemiarthroplasty in dept. we will discuss the historical use of these implants, as well as the intricacies of more modern devices. Next we will elaborate an surgical planning, approach, and technical pearls. We will lay out a rehab protocol used by the senior author, and with some considerations for the future.

The influence of polyethylene bearing thickness on the tibiofemoral kinematics of a bicruciate retaining total knee arthroplasty.

BACKGROUND: The recently reintroduced bicruciate retaining Total Knee Arthroplasty (BCR TKA) is an effort to reproduce kinematics closer to the native knee. However, there is no data on appropriate balancing with this implant. Balancing is crucial and challenging as medial and lateral polyethylene (PE) inlays are modular, which allows for placement of different thicknesses in the medial and lateral compartments. This study aimed at providing a detailed kinematic view on balancing BCR TKA. METHODS: Seven fresh frozen cadaver legs were mounted in a kinematic rig that applied squatting under application of physiologic quadriceps and hamstring forces. Additionally, specimen laxity was assessed using Lachman tests and varus/valgus stress tests. Following testing on the native knee, a BCR TKA was implanted in each specimen and all trials were repeated. Using one millimeter increments, five inlay thicknesses were tested to simulate optimal balancing, symmetric under-, and overstuffing, valgus constellation, and varus constellation. RESULTS: Overall, knee kinematics following BCR TKA seem to be very close to the native knee. The changes as introduced to tibiofemoral kinematics through over- or understuffing the polyethylene inserts are affecting the system only to a minor degree and generally lack statistical significance. Reproduction of the tibial varus via PE-Inlays did not lead to kinematics much closer to the native knee. CONCLUSIONS: The changes introduced to tibiofemoral kinematics by removal of the conforming meniscus and cartilage and replacement with a flat PE insert and femoral component are of more impact than different inlay sizes and their combinations for a BCR TKA.