Accurate component orientation and restoration of hip biomechanics remains a continuing challenge in total hip arthroplasty (THA). The goal of this study was to analyze the accuracy/reproducibility of a novel CT-free and pin-less robotic-assisted THA (RA-THA) platform compared to manual THA (mTHA). This matched-pair cadaveric study compared this RA-THA system to mTHA (n = 33/arm), both using the assistance of fluoroscopic imaging, in a group of 14 high-volume arthroplasty surgeons. In both groups, surgeons were asked to aim for 40°/15° for cup inclination/version, and 0 mm of leg length discrepancy (LLD). A validated and accurate method using radio-opaque markers measured cup inclination/version and LLD. The accuracy and reproducibility (fewer outliers) of cup inclination was significantly improved in the robotic group (1.8° ± 1.3° vs 6.4° ± 4.9°, respectively, robotic vs manual; p < 0.001), with no significant difference between groups for version. The reproducibility of LLD was significantly improved in the robotic group (p = 0.003). For all parameters studied, the robotic group had an improved accuracy and lower variance (fewer outliers). The percentage of cases within the more restrictive Callanan safe zone was 100% for RA-THA vs 73% for mTHA (p = 0.002). The CT-free RA-THA platform, using only fluoroscopic imaging, demonstrated more accurate acetabular cup positioning, when compared to the mTHA procedures performed by high-volume hip surgeons (naive to this RA-THA platform), with respect to cup inclination and placement within the Lewinnek/Callanan safe zones. Future study must incorporate economic factors, lower volume surgeons, clinical and patient-centric outcomes, and other radiographic parameters in controlled studies in large sample sizes.

Purpose Alignment errors in medial unicompartmental knee arthroplasty (UKA) predispose to premature implant loosening and polyethylene wear. The purpose of this study was to determine whether a novel CT-free robotic surgical assistant improves the accuracy and reproducibility of bone resections in UKA compared to conventional manual instrumentation. Methods Sixty matched cadaveric limbs received medial UKA with either the ROSA ® Partial Knee System or conventional instrumentation. Fifteen board-certiied orthopaedic surgeons with no prior experience with this robotic application performed the procedures with the same implant system. Bone resection angles in the coronal, sagittal and transverse planes were determined using optical navigation while resection depth was obtained using calliper measurements. Group comparison was performed using Student's t test (mean absolute error), F test (variance) and Fisher's exact test (% within a value), with signiicance at p < 0.05. Results Compared to conventional instrumentation, the accuracy of bone resections with CT-free robotic assistance was signiicantly improved for all bone resection parameters (p < 0.05), other than distal femoral resection depth, which did not difer signiicantly. Moreover, the variance was signiicantly lower (i.e. fewer chances of outliers) for ive of seven parameters in the robotic group (p < 0.05). All values in the robotic group had a higher percentage of cases within 2° and 3° of the intraoperative plan. No re-cuts of the proximal tibia were required in the robotic group compared with 40% of cases in the conventional group. ConclusionThe ROSA ® Partial Knee System was signiicantly more accurate, with fewer outliers, compared to conventional instrumentation. The data reported in our current study are comparable to other semiautonomous robotic devices and support the use of this robotic technology for medial UKA. Level of evidence Cadaveric study, Level V.

Conventional total knee arthroplasty and soft tissue balancing is based on a subjective unquantified assessment, which can lead to imperfect balancing and poor patient outcomes. Five case studies were used to present the functionality of a novel robotic system in allowing intraoperative adjustments based on objective measures for several primary total knee arthroplasty cases. The robotic system allows the surgeon to drive every step of the case, turning the subjective nature of conventional knee replacement into a more objective and scientific approach for restoration of alignment, gap balancing, joint space restoration, femoral rotation, and Q-angle restoration. The robotic system allowed precise intraoperative adjustments, as demonstrated by these cases, and is a promising step towards more personalized total knee arthroplasty made possible by utilizing real-time objective measures.

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A 72-year-old man presented with a 48-hour history of increasing left posterior thigh pain and a progressive left knee flexion contracture. Physical examination revealed that he recently had a left below knee amputation. The stump was healing well. He had a firm posterior thigh with a woody consistency extending from the popliteal fossa proximally to the midposterior left thigh. On attempted passive extension of the left knee, there was exquisite pain in the posterior thigh.Four weeks before his current presentation for the left posterior thigh pain, he had been admitted to our institution with a 1-week history of worsening abdominal pain, nausea, and vomiting. The patient had general surgery and gastroenterology consultations. Physical examination of his abdomen revealed a soft, nondistended abdomen with hyperactive bowel sounds. He had tenderness in the epigastrium, umbilical region, and right lower quadrant. There were no palpable masses or organomegaly. Imaging of the abdomen revealed a high-grade small bowel obstruction with a transition point seen in the right lower quadrant. The patient was treated with a small bowel follow-through and colonoscopy that led to an exploratory laparotomy with resection of a mass in the distal ileum. Pathologic examination of the small bowel mass showed a metastatic Stage IV carcinoma. Further immunohistochemical and tumor marker analyses suggested a primary neoplasm of gastric or esophageal origin. Staging with a CT of the chest, abdomen, and pelvis showed no other lesions of the viscera.During the same hospital admission for his small bowel obstruction, orthopaedics was consulted for a chronic 4-cm 9 2-cm wound of the left heel that had been present for 6 months. On evaluation, he also had chronic osteomyelitis of the left calcaneus and a left knee flexion contracture of 30°with mild tenderness to palpation about the knee. Radiographs of the left knee showed chronic degenerative changes. No additional or advanced imaging of his left knee or thigh was obtained at that time, as he had a relatively painless knee flexion contracture. His surgical history revealed that 2 years before his current presentation he had undergone a left Chopart amputation for dysvascular forefoot wounds. Although he did not have a diagnosis of diabetes, he had a history of peripheral vascular disease with neuropathy secondary to heavy tobacco use. As treatment for his chronic heel wound, the patient underwent a left below knee amputation 5 days after his exploratory laparotomy. Intraoperatively after the below knee amputation, he was treated with an intraarticular