The learning curve of imageless robot-assisted total knee arthroplasty with standardised laxity testing requires the completion of nine cases, but does not reach time neutrality compared to conventional surgery.

PURPOSE: The assistance of robot technology is introduced into the operating theatre to improve the precision of a total knee arthroplasty. However, as with all new technology, new technology requires a learning curve to reach adequate proficiency. The primary aim of this study was to identify the learning curve of an imageless robotic system with standardised laxity testing. The secondary aim of this study was to evaluate the accuracy of the intra-operative coronal alignment during the learning curve. METHODS: A prospective study was performed on 30 patients undergoing robot-assisted total knee arthroplasty with an imageless robotic system (Corin, Massachusetts, USA) associated with a dedicated standardised laxity testing device. The learning curve of all surgical steps was assessed with intra-operative video monitoring. As comparison, the total surgical time of the last 30 patients receiving conventional total knee arthroplasty by the same surgeon and with the same implant was retrospectively assessed. Coronal lower limb alignment was evaluated pre- and post-operatively on standing full-leg radiographs. RESULTS: CUSUM (cumulative summation) analysis has shown inflexion points in multiple steps associated with robot-assisted surgery between one and 16 cases, which indicates the progression from the learning phase to the proficiency phase. The inflexion point for total operative time occurred after nine cases. Robot-assisted total knee surgery required significantly longer operative times than the conventional counterpart, with an average increase of 22 min. Post-operative limb and implant alignment was not influenced by a learning curve. CONCLUSION: The introduction of an imageless robotic system with standardised laxity assessment for total knee arthroplasty results in a learning curve of nine cases based on operative time. Compared to conventional surgery, the surgeon is not able to reach time neutrality with the robotic platform. There is no learning curve associated with coronal limb or implant alignment. This study enables orthopaedic surgeons to understand the implementation of this surgical system and its specific workflow into clinical practice.

Addition-Subtraction Osteotomy With Ligamentoplasty for Symptomatic Trapezial Dysplasia With Metacarpal Instability: A 10-Year Follow-Up.

PURPOSE: Symptomatic trapezial dysplasia with metacarpal instability in a nonarthritic joint can lead to a disabling condition characterized by decreased pain, mobility, and strength. Bony correction may be required in dysplastic joints, because soft tissue correction might be insufficient to stabilize the trapeziometacarpal (TMC) joint. We combined 2 techniques described previously, an abduction-extension osteotomy of the first metacarpal and an opening wedge osteotomy of the trapezium, including a ligament reconstruction (hemi-flexor carpi radialis). The aim of this study was to investigate the long-term results of this technique. METHODS: In this single-center, retrospective cohort study, we included patients treated surgically for primary instability of the TMC joint with trapezial dysplasia between 2003 and 2007. We measured pain (visual analog scale), mobility (opposition and retropulsion), patient-reported disability (Quick-Disabilities of the Arm, Shoulder, and Hand), and radiographic evaluation (Devers' angle) 10 years after surgery. Results were compared with preoperative data. RESULTS: We reviewed 17 thumbs retrospectively (mean follow-up, 12 years). One patient was converted to a TMC prosthesis. Key pinch improved significantly from 5.2 kg (±2.4 kg) at baseline to 6.3 kg (±2.1 kg) at 10-year follow-up. Quick-Disabilities of the Arm, Shoulder, and Hand score and Devers' angle were significantly better after 10 years compared with preoperative data. There was a mean visual analog scale score of 0.5 (±1.4) at rest and 2.3 (±2.6) during activities. Ten years after surgery, 5 patients had a stable Eaton score of 1. Four patients had progression to stage 2, and 5 to stage 3. CONCLUSIONS: Addition-subtraction osteotomy with ligamentoplasty has a positive long-term effect on symptomatic trapezial dysplasia with TMC joint instability. Although this operation did not protect the TMC joint from further wear, pain was acceptable for most patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Reduced joint awareness after total knee arthroplasty with a cruciate retaining design.

A range of different total knee arthroplasty (TKA) designs have been developed, each specifically designed to relieve pain and restore knee function with the greatest possible patient satisfaction. The purpose of this study was to compare a posterior stabilized design and a cruciate-retaining design. We hypothesized that a cruciate-retaining design would have a higher Forgotten Joint Score (FJS) than a posterior stabilized design. Ninety-two patients were used in our analysis (46 patients in each group) involving TKA (Attune, Depuy-Synthes) between January 2014 and March 2015. We excluded patients with valgus alignment, post-traumatic arthritis, rheumatoid arthritis and major previous surgery on the knee. We compared the FJS, the Oxford Knee Score (OKS) and their ceiling effects. FJS was significantly higher in the fixed-bearing cruciate-retaining group (P=0.043). The mean (-SD) FJS for the cruciate-retaining group was 78,4-25.1 compared to 67.6-27.6 for the posterior stabilized group. No significant difference in OKS was detected. The total ceiling effect for FJS and OKS was 32.2% and 45.5%, respectively. In conclusion, patients with cruciate-retaining TKA showed a better FJS in comparison to posterior stabilized TKA. FJS has a higher discriminatory power compared to OKS.

Measurement of ulnar variance and radial inclination on X-rays of healed distal radius fractures. With the axis of the distal radius or ulna?

Ulnar variance and radial inclination are radiological parameters frequently used to evaluate displacement of distal radius fractures. In most studies measurements are based on the long central axis of the distal radius, although the axis of the distal ulna can also be used. The purpose of this study was to determine which axis is more reliable. Four observers performed measurements on standard anteroposterior digital wrist X-rays of 20 patients taken 1 and 2 months after sustaining an extra-articular distal radius fracture. Intraobserver reliability was similar with both methods. No difference was found in interobserver reliability between both methods for ulnar variance, but for radial inclination it was better with the axis through the radius. Measurements on two X-rays of the same wrist taken at a different moment were similar with both methods. It can be concluded that the central axis of the distal radius can remain the basis to determine ulnar variance and radial inclination.