Gait analysis is an indispensable tool for scientific assessment and treatment of individuals whose ability to walk is impaired. The high cost of installation and operation are a major limitation for wide-spread use in clinical routine.

Advances in Artificial Intelligence (AI) could significantly reduce the required instrumentation. A mobile phone could be all equipment necessary for 3D gait analysis. MediaPipe Pose provided by Google Research is such a Machine Learning approach for human body tracking from monocular RGB video frames that is detecting 3D-landmarks of the human body.

Aim of this study was to analyze the accuracy of gait phase detection based on the joint landmarks identified by the AI system.

Motion data from 10 healthy volunteers walking on a treadmill with a fixed speed of 4.5km/h (Callis, Sprintex, Germany) was sampled with a mobile phone (iPhone SE 2nd Generation, Apple). The video was processed with Mediapipe Pose (Version 0.9.1.0) using custom python software. Gait phases (Initial Contact - IC and Toe Off - TO) were detected from the angular velocities of the lower legs. For the determination of ground truth, the movement was simultaneously recorded with the AS-200 System (LaiTronic GmbH, Innsbruck, Austria).

The number of detected strides, the error in IC detection and stance phase duration was calculated.

In total, 1692 strides were detected from the reference system during the trials from which the AI-system identified 679 strides. The absolute mean error (AME) in IC detection was 39.3 ± 36.6 ms while the AME for stance duration was 187.6 ± 140 ms.

Landmark detection is a challenging task for the AI-system as can clearly be seen be the rate of only 40% detected strides. As mentioned by Fadillioglu et al., error in TO-detection is higher than in IC-detection.

Introduction: Less invasive surgical technique in THA is expected to minimize soft tissue damage and expedite rehabilitation. Due to this, it is now in widespread use in elective THA. The large geriatric patient population suffering a fractured neck of femur thereby would also benefit of this technique. Aim of this study was to evaluate if this technique is feasible in the non-elective setting of geriatric patients and if there are benefits regarding clinical and social outcome.

Patients and Methods: Study setup is a prospective randomized trial with a positive Ethical Committee vote. Included were patients under legal care of a third party. Inclusion criteria were the indication for bipolar hip arthroplasty including grade ASA 4; exclusion criteria included neoplastic disease and rheumatoid arthritis. Setting is a large university hospital. After biometrical evaluation, each arm was set as 30 patients. Primary end point was the modified Barthel index. 48 patients were female. Mean age for female patients was 85.5, for male 82.9 years. There was no detectable difference in the groups regarding age, sex and BMI. As a less invasive approach, the well described „Direct Anterior Approach-DAA”(modified Smith-Petersen approach) was chosen. In the other arm the Watson-Jones approach was used. The ABG II stem with a bipolar UHR head (Stryker) were used in both groups. To minimize the learning curve, 10 cadaver- and 15 clinical procedures were performed with the DAA approach before the study. The pre- and postoperative regimen was identical in both arms. The modified Barthel index and other clinical parameter were determined preoperatively and at 4 postoperative intervals up to 40 days.

Results: There were no statistical differences between both groups for intra- and postoperative complications. The mean theatre time was 4.8 minutes longer for the DAA group, in the first 10 patients this difference was measured with 16 minutes. The Barthel Index was only statistically different at 40 days, at this time the DAA patients had reached their preoperative mobility level whilst the conventional approach patients (with a pre-operative level of 42.5) were measured with 25 points. The hemoglobin levels on day 5 and 16 were significantly different with a higher Hb for the DAA group. All other parameters showed no significant difference.

Conclusion: The DAA approach has a clear learning curve. Once this has passed, the theatre time is only slightly longer. There is a detectable benefit regarding early rehabilitation and a slight but significantly reduced blood loss.

Cemented modular metal backed total hip prostheses have the theoretical advantage to allow different inlays to be used. Asymetric or snap inlays are some of the options. First attempts with this kind of implant failed due to PE quality. A novel implant has been specifically designed and constructed for the use of cement. In vitro testing has shown results equal to other cemented cups. Aim of this study is to investigate the first clinical results of this implant with special consideration to intraoperative complications, intraoperative change of inlays, postoperative complications and clinical results.

Patients and Methods: Study setup was prospective, location a university hospital, approval for this study was granted by the local ethical committee. Inclusion criteria were patients with a biological age over 70 years that suffered a recent fractured neck of femur with the general indication for arthroplasty. Exclusion criteria were the inability for full informed consent, ASA IV and current infection. Thirty patients were included in this study. Mean age was 78.6 years (55.1 to 88.6), 23 patients were female (77%). The mean BMI was 25.3 (17.5–41).

The implant under investigation was a cemented modular acetabular component (C-MIC, ESKA Implants, Germany). The inlays are manufactured of highly crosslinked polyethylene. The standard protocols regarding DVT prophylaxis and antibiosis for HHS and the Barthel index.

Results: Implantation of the C-MIC component was possible in all cases. In 1 case (3.3%) the inlay was changed and replaced by an asymmetrical anti-luxation inlay intraoperatively as there was a luxation tendency. There were no other intraoperative complications. There was no case of infection or significant hematoma. In 1 case there was a DVT of the lower leg diagnosed by ultrasound on day 21. The mean Barthel index preop. was determined with 96.5 of 100, the mean Harris Hip Score with 89. At 3 months F/U the Barthel index was mean 96.1, at 6 months 96. The Harris Hip Score at 3 months was mean 72 points (17 pts below the preoperative status), at 6 months mean 79 points (10 pts below preoperative status).

Discussion: The C-MIC acetabular component does not show increased complication rates when compared to published results of hemiarthroplasty. The Barthel index as an outcome measurement of mobility and activities of daily living showed a return to the preoperative level. The HHSshowed a satisfactory result at 12 weeks, it also showed that patients of a geriatric population have problems to regain their full hip function after a fractured neck-of-femur.

We can conclude that the C-MIC acetabular component is safe to use. Due to limitations of this study we are not able to state if THA is superior to hemiarthroplasty in geriatric patients.

Introduction: Trauma surgeons are often less exposed to large caseloads of primary osteoarthritis, compared to purely “elective”orthopaedic surgeons. The experience in total knee arthroplasty is thereby markedly On the other hand, posttraumatic knee arthrosis is often accompanied by severe deformity and axis deviation. In theory, navigated arthroplasty can overcome some of the problems in this setting.

Aim: Evaluation of the navigated technique of total knee arthroplasty (TKA), including the technical difficulties, the learning curve and the feasibility in severe bony deformity. Setting is a level I trauma center. Study setup was prospective, follow up period on average 14.5 months (11–25 months).

Patients: Between 7/04–6/05 we treated 36 patients with arthritis of the knee related to trauma. 18 patients were male. Average age at TKA was 59 (32–77) years. On average patients had 2.83 previous operations.

Methods: The navigational system used is manufactured by PRAXIM (La Tronche/France). It uses infrared-tracking and bone-morphing software. The implant was a mobile bearing LCS knee (DePuy/USA). Follow up included radiographs, clinical examination and the knee society scores.

Results: In three cases the procedure was finished in a conventional technique, reasons were suspicion of the surgeon about the cuts recommended by the system, a missing femoral cut block and a broken screw of the tracker-fixation. There was no failure of the navigational system. There was a clear learning curve regarding procedure time. Preop mean extension deficit was improved from av. 7.1° (0–30°) to 1.67° (0°–10°) postop., flexion contracture improved from av. 95° to 103°. The combined knee society score (max. 200 pts) improved from 77 pts preop to 156 pts at follow up.

Conclusions: Navigated knee endoprosthesis is reliable tool for the trauma surgeon with few technical problems. Especially for surgeons with less experience in TKA, planning of implant size and position is very helpful. With posttraumatic deformity the surgeon can gain valuable information and assistance to improve alignment and ligamentous balancing.