Quantitative Evaluation of the Thickness of the Available Manipulation Volume Inside the Knee Joint Capsule for Minimally Invasive Robotic Unicondylar Knee Arthroplasty.

OBJECTIVE: Developing robotic tools that introduce substantial changes in the surgical workflow is challenging because quantitative requirements are missing. Experiments on cadavers can provide valuable information to derive workspace requirements, tool size, and surgical workflow. This work aimed to quantify the volume inside the knee joint available for manipulation of minimally invasive robotic surgical tools. In particular, we aim to develop a novel procedure for minimally invasive unicompartmental knee arthroplasty (UKA) using a robotic laser-cutting tool. METHODS: Contrast solution was injected into nine cadaveric knees and computed tomography scans were performed to evaluate the tool manipulation volume inside the knee joints. The volume and distribution of the contrast solution inside the knee joints were analyzed with respect to the femur, tibia, and the anatomical locations that need to be reached by a laser-cutting tool to perform bone resection for a standard UKA implant. RESULTS: Quantitative information was determined about the tool manipulation volume inside these nine knee joints and its distribution around the cutting lines required for a standard implant. CONCLUSION: Based on the volume distribution, we could suggest a possible workflow for minimally invasive UKA, which provides a large manipulation volume, and deducted that for the proposed workflow, an instrument with a thickness of 5-8 mm should be feasible. SIGNIFICANCE: We present quantitative information on the three-dimensional distribution of the maximally available volume inside the knee joint. Such quantitative information lays the basis for developing surgical tools that introduce substantial changes in the surgical workflow.

Functional limitations after lateral column lengthening osteotomy of the calcaneus are associated with lower quality of life.

PURPOSE: The purpose of this study was to quantify limitations in sagittal ankle range of motion (ROM) at least two years after lateral column lengthening osteotomy of the calcaneus (LLC) and their implications regarding quality of life. METHODS: Fifteen patients with a mean follow-up of 80 ± 27 months after LLC and 15 age-matched healthy persons participated in this study. Ankle joint complex ROM in plantarflexion and dorsiflexion was measured bilaterally using a goniometer and fluoroscopy (patients only). Quality of life was assessed using the short-form health questionnaire (SF36). Differences in ROM parameters (for the tibiotalar and subtalar joint) between sides (affected vs. unaffected) and between groups (patient vs. controls) and the relationship between ROM parameters and quality of life scores were assessed. RESULTS: ROM of the ankle joint complex on the affected side in patients was smaller than on the contralateral side (goniometer and fluoroscopy) and in healthy persons (goniometer; all P < .05). Among patients, SF36 total and pain scores, respectively, correlated with ROM of the subtalar joint (fluoroscopy; R = 0.379, P = 0.039 and R = 0.537, P = 0.001). Among patients and healthy persons, those with smaller dorsiflexion (goniometer) had lower quality of life scores. CONCLUSIONS: The smaller sagittal ROM of the affected ankle joint complex compared with the contralateral foot and healthy controls was mainly explained by limitations in the tibiotalar joint. Because of its association with quality of life, ROM should be considered in the treatment and rehabilitation planning in patients who are candidates for LLC.

Challenging Implantation of Hip Prosthesis in a 32-year-old Patient with Kniest Syndrome.

INTRODUCTION: Kniest dysplasia is associated with short body stature (dwarfism) and impairment of the musculoskeletal system due to a mutation in the COL2A1 gene coding for a protein that forms type II collagen. Hip endoprosthesis for patients with Kniest system requires a specific femoral shaft design since the medullar space is limited due to the underlying dysplasia. The Wagner cone stem has shown excellent results. It is especially suitable for patients with small or dysplasic femur. However, no data exist regarding hip endoprosthesis in a patient with Kniest syndrome. CASE REPORT: A 32-year-old female patient with Kniest syndrome presented at our department with a painful pseudarthrosis after femoral valgisation osteotomy 8 years ago. A Wagner cone stem and acetabular roof cup with a cemented Ecofit cup 2M (dual-articulation acetabular cup system) were implanted due to a dysplastic femur with a small medullary space. The Ecofit cup itself is associated with a reduced risk of dislocation. The patient was satisfied with the range of motion after hip endoprosthesis and reported a significant increase in quality of life. The patient is still comfortable with the hip prosthesis at the most recent follow-up 4 years after implantation. Follow-up radiographs over 4 years have not revealed any signs of loosening or migration, and no Trendelenburg sign was reported for the affected side. CONCLUSION: The Wagner cone stem provides a good solution in challenging femora caused by previous osteotomies, fractures, or dysplasia. Additional stability of hip prosthesis can be achieved using a dual articulation acetabular cup system. Furthermore, we applied an attachment tube based on the concept of tumorprosthesis where the abductor muscle group got reattached.

Does the applied polytrauma definition notably influence outcome and patient population? - a retrospective analysis.

BACKGROUND: Although the term "polytrauma" has been in use for decades, no generally accepted definition exists. The aim of this study was to demonstrate that different polytrauma definitions applied to a specific patient population result in diverse subgroups of individuals, who in turn present a varying outcome. METHODS: All patients (≥18 years) treated at our level I trauma center within a time period of three years were classified according to 11 selected polytrauma definitions and included in our study, if they were rated "polytraumatized" by at least one of these definitions. All patients, who met the criteria of a certain definition, were combined to the relevant definition-positive group, thus resulting in 11 patient subgroups. Their demographic data (number of patients, mean patient age, mean Injury Severity Score value, median number of ventilator days, median length of stay at the intensive care unit and at the hospital, mortality rate and odds ratio) were statistically compared. RESULTS: Three hundred seventy-five patients (73% male) with a mean age of 47 years met the inclusion criteria and were allocated to the relevant subgroups; their patient number varied from 55 to 346 and their mean Injury Severity Score value ranged from 4 to 75. Not surprisingly, all examined parameters were subject to variations. Whereas most definition-positive groups showed a mortality rate of about 21% to 30%, 18% of the individuals, who met the criteria according to Blacker, and 40% of the polytrauma victims according to Schalamon died. The Pape 1-, Schalamon-, and Berlin-positive groups presented a significant odds ratio with regard to mortality that considerably exceeded 1. DISCUSSION: A polytrauma definition can only be a reliable tool in classifying trauma victims if it provides a significant odds ratio with regard to mortality that considerably exceeds 1 and if it succeeds in capturing patients with multiple severe injuries and a higher mortality rate without reducing the number of polytraumatized patients to a not representatively small number. CONCLUSIONS: Solely the Berlin definition resulted in a patient number reflecting clinical reality, thus enabling a transparent evaluation of treatment results provided by different institutions and allowing objective comparison of published studies.