Accurate component positioning and planning is vital to prevent malalignment of total knee arthroplasty (TKA) as malalignment is associated with an increased rate of polyethylene wear and revision arthroplasty. The MAKO total knee robotic arm-assisted surgery (Stryker, Kalamazoo, MI) uses a preoperative computed tomography scan of the patient's knee and three-dimensional planning to size and orientate implants prior to bone resection. The aim of this study was to determine the accuracy of the MAKO Total Knee system in achieving the preoperative plan for bone resection and final limb coronal alignment. A series of 45 consecutive cases was performed using the MAKO Total Knee system and Triathlon Total Knee implant (Stryker) between April 2018 and May 2019. The difference between what was planned and what was achieved for bone resection and coronal limb alignment was calculated. A total of 37 patients had their data captured using the MAKO system software. Mean difference from the plan for distal femoral cuts was 0.38mm (0.32) deep/proud, anterior femoral cuts 0.44mm (0.27) deep/proud and tibial cuts 0.37mm (0.30) deep/proud. In total, 99 out of 105 (94.29%) of bone resections were within 1mm of the plan. Mean absolute difference in final limb coronal alignment was 0.78° (0.78), with 78.13% being ≤1.00° of the plan, and 100% being ≤3.00° of the plan. The accuracy in achieving preoperatively planned bone resection and final limb coronal alignment using the MAKO Total Knee system is high. Future research is planned to look at whether this is associated with decreased rates of polyethylene wear and revision arthroplasty.

SHP-1 is a Src homology 2 (SH2) domain-containing tyrosine phosphatase that plays an essential role in negative regulation of immune cell activity. We describe here a new model for regulation of SHP-1 involving phosphorylation of its C-terminal Ser 591 by associated protein kinase C␣. In human platelets, SHP-1 was found to constitutively associate with its substrate Vav1 and, through its SH2 domains, with protein kinase C␣. Upon activation of either PAR1 or PAR4 thrombin receptors, the association between the three proteins was retained, and Vav1 became phosphorylated on tyrosine and SHP-1 became phosphorylated on Ser 591 . Phosphorylation of SHP-1 was mediated by protein kinase C and negatively regulated the activity of SHP-1 as demonstrated by a decrease in the in vitro ability of SHP-1 to dephosphorylate Vav1 on tyrosine. Protein kinase C␣ therefore critically and negatively regulates SHP-1 function, forming part of a mechanism to retain SHP-1 in a basal active state through interaction with its SH2 domains, and phosphorylating its C-terminal Ser 591 upon cellular activation leading to inhibition of SHP-1 activity and an increase in the tyrosine phosphorylation status of its substrates.The reversible phosphorylation of Tyr residues is an important mechanism regulating protein function. The Tyr phosphorylation status, and subsequently the activity, of many proteins is determined by the opposing actions of kinases and phosphatases that are in many cases themselves regulated by phosphorylation. There are large numbers of protein-tyrosine kinases and protein-tyrosine phosphatases with distinct substrate specificity and modes of regulation. The SH2 1 domain containing tyrosine phosphatases SHP-1 and SHP-2 are members of the protein-tyrosine phosphatase superfamily (1) and possess a catalytic domain with two SH2 domains at the N terminus and a C-terminal tail of poorly characterized function. Although closely related in structure, the roles of SHP-1 and SHP-2 in cells have been shown to be quite different. SHP-1 plays a largely negative signaling role (2) maintaining proteins in an inactive un-phosphorylated state, whereas SHP-2 plays a largely positive signaling role leading to cellular activation (3). The underlying reason for their different roles, despite structural similarity, is still not clear but may partially reside in different mechanisms of regulation of the phosphatases.Solving the crystal structures of the C-terminally truncated versions of, first, SHP-2 (4) and, second, SHP-1 (5) has lead to the proposal of a model where the inactive conformation of SHPs is maintained by the N-SH2 domain, which occludes the active site of the enzyme, thereby inhibiting the phosphatase activity. The C-SH2 domain, which has minimal interaction with the catalytic domain, is then responsible for selecting substrates (6). This model was supported by earlier mutagenesis studies of SHP-1 showing that removal of the SH2 domains increased the phosphatase activity at physiological pH (7), and another study refined this further ...

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We present patient outcomes following surgical excision of primary wrist ganglia over a 5 year period. Patients (48 of 59; 81%) responded to a questionnaire by post or telephone, with a mean time to follow-up of 44 (range 21-77) months. There was a statistically significant reduction in all reported symptoms, including pain, paraesthesia, weakness, stiffness, and cosmesis. The recurrence rate was 8%. In total, 98% of patients were satisfied or very satisfied with treatment. Surgical excision of primary wrist ganglia may have advantages over aspiration and reassurance alone, particularly in reducing recurrence and hastening resolution of symptoms.

Both trapeziectomy and the ARPE CMCJ arthroplasty are effective treatment options for thumb CMCJ osteoarthritis. Arthroplasty may offer potential advantages in terms of post-operative function and patient satisfaction. However the risk of complications and requirement for further surgery is greater and must be carefully considered during patient selection and pre-operative counselling.

Weight-bearing status and ankle joint position should be appreciated during decisions for the provision of chemical thromboprophylaxis.

Thumb carpometacarpal joint (CMCJ) arthritis is a common and painful condition. Thumb CMCJ prosthetic replacement aims to restore thumb biomechanics and improve pain and function. Early reviews demonstrated a lack of high-quality studies, but more recently a significant number of higher-quality studies have been published. This review provides a concise and systematic overview of the evidence to date. A systematic review of several databases was conducted according to PRISMA guidelines. Studies evaluating the outcomes of thumb CMCJ prosthetic total joint replacement were included. Data extracted included patient-reported outcome measures (PROMs), pain scores, range of motion, strength, survival rates and complications. A total of 56 studies met all inclusion criteria and were analysed. There was one randomized controlled trial, three prospective comparative cohort studies, five retrospective comparative cohort studies, and 47 descriptive cohort studies. The reported studies included 2731 patients with 3048 thumb total CMCJ prosthetic joint replacements. Follow up ranged from 12 months to 13.1 years. In general, good results were demonstrated, with improvements in PROMs, pain scores and strength. Failure rates ranged from 2.6% to 19.9% depending upon implant studied. Comparative studies demonstrated promising results for replacement when compared to resection arthroplasty, with modest improvements in PROMs but at a cost of increased rates of complications. Studies reporting outcomes in thumb CMCJ prosthetic total joint replacement are increasing in both number and quality. Failure, in terms of loosening and dislocation, remains a concern, although in the medium-term follow up for modern implants this issue appears to be lower when compared to their predecessors. Functional outcomes also look promising compared to resection arthroplasty, but further high-quality studies utilizing a standardized resection arthroplasty technique and modern implants, together with standardized core outcome sets, will be of value. Cite this article: EFORT Open Rev 2021;6:316-330. DOI: 10.1302/2058-5241.6.200152

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