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Background: Unicompartmental knee arthroplasty (UKA) is an established surgical treatment option for end-stage anteromedial osteoarthritis with excellent functional outcomes and implant survival. Routine preoperative varus and valgus stress views are crucial for the selection of patients for unicompartmental or total knee arthroplasty., Therapy: UKA is a soft-tissue based operation that aims to reconstruct the individual joint line and pre-arthritic alignment by restoring the physiological tension of the medial collateral and the cruciate ligaments., Results: Current data for medial UKA show excellent results for both mobile and fixed bearing implant designs with the correct indication and surgical technique. Cementless fixation offers potential advantages over cemented implants. Registry data demonstrate that institutions and surgeons specializing in partial knee replacement (> 30 cases/year per surgeon, > 100/year per institution) with a high percentage of UKA relative to the total number of knee implants (> 20%) have significantly lower revision rates., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Numerous long-term results for both medial and lateral unicondylar knee arthroplasty (UKA) demonstrate that UKA is a reliable and successful treatment for isolated anteromedial or lateral osteoarthritis of the knee when the correct indications are used. The relationship between operation volume and implant performance has clearly been established from recent studies and registry data. The use of novel technologies allows for an improvement in the accuracy of implant positioning with fewer outliers. However, evidence-based target zones for the positioning of available implants have not been sufficiently established., Individual Endoprosthetics: Current data does not support the routine use of patient-specific instruments or custom-made implants., Robotics: Robot-assisted procedures must be interpreted as a very promising approach for the future. So far, there is insufficient evidence that robotically assisted surgical techniques improve implant performance or lead to better functional results from the patient's point of view.

Objective: Joint surface replacement in the lateral compartment by unicondylar knee arthroplasty., Indications: Lateral unicompartmental osteoarthritis of the knee joint, avascular necrosis of the lateral femoral condyle., Contraindications: Full thickness cartilage defect in the central part of the medial compartment or in the medial aspect of the patellofemoral joint. Instability/contracture of cruciate and collateral ligaments, valgus deformity >15°, valgus deformity not passively correctable, flexion deformity >15°, an intraoperative flexion <100°, failed upper tibial osteotomy, rheumatoid arthritis., Surgical Technique: Leg positioning in leg holder. Minimally invasive parapatellar lateral arthrotomy. Exposure of the lateral compartment and removal of osteophytes. Attachment of the tibial saw guide. Horizontal cut 7-8 mm below the original tibial plateau with protection of the lateral collateral ligament. Vertical saw cut via an incision in the central aspect of the patellar ligament with an internal rotation of 20°. Femoral preparation. Insertion of the intramedullary rod, positioning of the femoral drill guide directing to the anterior superior iliac spine and drilling the holes. Insertion of the posterior resection guide. Saw cut with protection of the lateral collateral ligament. Insertion of the 0 mm spigot and first milling. Measurement of the extension gap. Insertion of the corresponding spigot (never use a spigot >5 mm). Milling and insertion of the trial components. Application of the anti-impingement guide and anterior and posterior resection of bone. Final preparation of the tibial plateau. Cementing of the components., Postoperative Management: Mobilization under full weight-bearing with two crutches., Results: With a mean follow-up of 1.7-4 years, the dislocation rate is about 0-6.6%. Revision-free survival is 90-98%.

Beside the possibility of bicondylar knee replacement, patients with isolated anteromedial osteoarthritis also have the possibility of unicondylar knee replacement. Therefore some requirements are essential such as functionally intact cruciate and collateral ligaments, intact cartilage in the lateral compartment and an intraoperative flexion of more than 100°. An instability or contracture of the cruciate or collateral ligaments, a varus deformity more than 15°, a flexion deformity of more than 15°, an intraoperative flexion less than 100° as well as failed upper tibial osteotomy are seen as contraindications. In addition, a rheumatoid arthritis and a full thickness cartilage defect in the central part of the lateral compartment are seen as a contraindication because of the risk of a progression of the disease. With respect to these contraindications, excellent functional outcome and survival rates could be demonstrated in the long term. An expansion of these criteria, especially in patients with an insufficiency of the cruciate ligaments or after failed upper tibial osteotomy should only be done in certain cases after careful assessment of the benefits and risks. These patients should be informed about the lack of long-term results and the higher risk of complications. Quite commonly, the criteria of Kozinn and Scott are used for patient selection. These criteria were originally established for fixed-bearing prosthesis and have no relevance on mobile-bearing prosthesis. Criteria such as age, level of activity, weight, chondrocalcinosis and anterior knee pain have no effect on the clinical outcome or the long-term survival of a mobile-bearing prosthesis., (Georg Thieme Verlag KG Stuttgart · New York.)

The term anteromedial osteoarthritis of the knee joint was first established in 1991 by White et al. and describes an isolated osteoarthritis of the medial tibiofemoral compartment with intact posterior tibial cartilage in patients with a functionally intact anterior cruciate ligament and occurs in about 30 % of all patients with clinically relevant gonarthrosis. In these patients, there is the possibility for minimally invasive unicondylar knee arthroplasty. One of the most commonly used prosthesis with long-term experience is the Oxford Uni knee prosthesis (Biomet UK Limited, Swindon, UK). The most recent phase of development of this prosthesis focused on improving the reliability of the instruments (Microplasty) which allows a more reproducible execution of the operation to help eliminate early failure due to surgical errors. In the following article, the essential surgical steps of minimally invasive implantation of the Oxford Uni with the Microplasty instrumentation in a patient with severe anteromedial osteoarthritis of the knee joint are demonstrated and explained., (Georg Thieme Verlag KG Stuttgart · New York.)

Background: Unicompartmental osteoarthritis of the knee joint affects the medial compartment more often than the lateral compartment whereby the lateral is solely affected in only 5-10 % of cases. In this case unicompartmental knee arthroplasty has been shown to be an effective alternative to total knee arthroplasty. There are some basic anatomical and biomechanical differences between the medial and lateral compartment of the knee joint which directly influence modern surgery techniques and implant design. In general, kinematics and design are fundamentally different in mobile-bearing compared to fixed-bearing prostheses., Objectives: This article presents a summary of outcome and survival rates after unicompartmental knee arthroplasty in the lateral compartment., Methods: This article is based on a literature search in the PubMed database for clinical results after lateral unicompartmental knee arthroplasty., Results: The results demonstrate that lateral unicompartmental knee arthroplasty with a mobile-bearing implant and a domed tibial plateau design gives an excellent clinical outcome while reducing the dislocation rate to an acceptable level in the short and mid-term. Published data on the clinical outcome of fixed-bearing lateral unicompartmental knee arthroplasty prostheses revealed heterogeneous results due to the inclusion of different implant designs and relatively small patient cohorts. Nevertheless, most of them demonstrated good clinical results with a longer follow-up than current studies concerning mobile-bearing prostheses., Conclusion: Based on the published data it is not possible to demonstrate precise differences in clinical outcome and survival rates after mobile-bearing and fixed-bearing unicompartmental knee arthroplasty or to make clear recommendations on the use of each type of prosthesis.

Aim: The purpose of this clinical study (matched-pair design) was to compare the functional short-term results obtained in patients with surface replacement of the humeral head and cemented glenoid prosthesis with those obtained after total shoulder arthroplasty., Method: 20 patients (average age 67.7 [43-85] years, 17 women, three men) who received surface replacement of the humeral head with cemented glenoid prosthesis were matched to a control group of 20 patients (average age 67.55 [42-85] years, 17 women, three men) with a conventional total shoulder arthroplasty. Six patients were treated for osteoarthritis, two for post-traumatic arthritis, 1 each for osteonecrosis and rheumatoid arthritis. Preoperative status, perioperative results and postoperative status (Constant score, subjective assessment, range of motion, radiographic evaluation) were compared in all patients and controls., Results: The adjusted Constant score improved from a mean of 37.25% to a mean of 87.75% in the hybrid group and from a mean of 30.8% to a value of 87.1% in the TSA group. Regarding the relative improvement at 12 months compared to baseline, patients treated with hybrid prostheses showed a comparable benefit in the Constant score, pain reduction and range of motion. Only the criterion "strength" revealed a significantly better result in the TSA group (p = 0.025). There was one irreversible injury of the brachial plexus in one case and neural injuries with a full recovery in two cases of Hybrid prosthesis., Conclusions: The combination of humeral surface replacement with cemented glenoid component offers a relatively new option for the treatment of different pathologies at the shoulder joint which need a total joint substitute.The short-term results are comparable with those of conventional total shoulder arthroplasty. Surface replacement of the shoulder facilitates later revision because of less loss of bone stock. It must be considered that surface replacement with implantation of cemented glenoid prosthesis is a difficult procedure because of the exploration of the glenoid., (© Georg Thieme Verlag KG Stuttgart · New York.)

Background: The use of uncemented femoral components in primary total hip arthroplasty has become a standard procedure with increasing numbers. In contrast to the well-established long-term results of cemented femoral stems, true long-term data on the survival of uncemented femoral components are rare. With regard to high patient demands and increasing cost pressures in the public health system, long-term outcomes of uncemented femoral stems are crucial to further support their clinical use., Material and Methods: We conducted a systematic literature research in Medline to obtain long-term survival rates of uncemented femoral stems. Strict inclusion criteria concerning patient numbers (n>50 hips for single studies, n>150 hips for register data), follow-up time (minimum 15 years), and patients lost to follow-up (<10%) were established to identify substantial studies. The minimum 15-year survival rates of published single studies and data from arthroplasty registers were extracted in a literature analysis., Results: Nineteen studies (17 single studies and two studies with data from arthroplasty registers) that met the inclusion criteria were identified. Survival rates for 16 different uncemented femoral stems were obtained. For most implants included in the study, the long-term outcomes of uncemented femoral components in total hip arthroplasty show minimum 15-year survival rates of over 90% independent of patient age., Conclusion: The long-term results with a minimum follow-up of 15 years are good or excellent for most studied uncemented femoral stems and are comparable to the outcomes of cemented femoral components. The existing data confirm the previously reported promising midterm results. Therefore, the clinical use of uncemented femoral stems should be considered a reliable treatment option for all patients with adequate bone quality.

Background: Acetabular revision in total hip arthroplasty (THA), especially for loose or migrated cup components with collateral bone loss, remains a great surgical challenge. The aim should always be a functionally favorable reconstruction of the rotation center with sufficient load capacity of the acetabulum. Commonly used implants in Europe are the Mueller ring, the Ganz ring, and the Burch-Schneider cage., Patients and Methods: We report our results of 298 patients (298 hips) with a median follow-up period of 4 (range 0-17) years in a retrospective series., Results: Follow-up data were available in 224 cases (75%). A radiographic examination was performed in 176 (59%) patients. Another 54 patients (18%) had died in the follow-up period, while another three patients (1%) were lost to follow-up. Eighteen patients (16%) underwent re-revision, in nine cases for aseptic loosening and in the remaining nine cases for infection. In seven additional cases (2%), radiological and clinical failure was found during follow-up. The overall survival rate was 94% at 5 years and 89% at 8 years., Conclusion: Revision THA using acetabular reinforcement rings results in acceptable midterm results. However, septic complications and lysis of the bone graft with consecutive failure of the reinforcement ring remain problematic.

We conducted this pilot cadaver study to investigate whether the use of a navigation system during minimally invasive unicompartmental knee arthroplasty leads to more consistent results than the conventional hand-guided technique. We describe the accuracy of implant positioning in using standard instrumentation and computer navigation. Radiographic assessment showed that accurate component placement was achieved using both methods. These results were not statistically significant. The computer navigated femoral component placement without intramedullary (IM) rod was as accurate as the conventional method with IM rod. The study showed that computer navigation can produce accurate results even without an intramedullary rod. Image guidance can maintain the accuracy of the standard instrumentation and enhance 3D vision and the intraoperative orientation of the surgeon.

Medial unicompartmental knee replacement (UKR) has many advantages over total replacement (TKR) including better function and reduced morbidity. However, the long-term failure rates of fixed-bearing UKR are high, especially because of polyethylene wear. The fully congruent mobile bearing of the Oxford UKR exhibits minimal polyethylene wear, failure from this cause does not seem to occur before 10 years. The instrumentation allows precise implantation to restore isometric function of the ligaments. During its 20 years development, the limits of usefulness of the implant have been established and found to include about one in four knees requiring replacement for osteoarthritis. In an independent series, using these criteria, the 15 year survival was 94%. Since 1998, the phase 3 implant has been used with modified instruments through a small incision, avoiding damage to the extensor mechanism. Patients now recover about three times faster than after TKR, and regain much better flexion (mean 135 degrees ). The current evidence supports that the minimally invasive Oxford UKR should be seriously considered as primary treatment for anteromedial compartment osteoarthritis-provided the appropriate surgical expertise is available.

The use of ultrasonic instruments to remove PMMA bone cement during revision hip arthroplasty results in the production of fumes. These emissions were analysed under standardized laboratory conditions, when it was found that the MMA concentration measured was only 1/10th of the MAC value. In terms of occupational safety, the MMA fumes emitted may therefore be considered non-hazardous for the medical personnel.

In this review the different anchorage concepts of cemented and cementless acetabular components are presented and clinical long-term results--if available--are discussed. Despite numerous design improvements and modifications the long-term durability of acetabular components remains a major concern with results being clearly inferior than achieved with femoral components. Until valid, prospective long-term success is proven for cementless designs cemented acetabular fixation using modern cementing technique must be regarded as standard treatment. However, successful fixation over 15-20 years very much depends on the quality of operative and cementing technique. Some cementless systems appear easier to use and have been documented to offer reliable mid-term survival rates. In young patients cementless devices have been well established and for some systems promising 10-year results have been published.

Total hip replacement is one of the most successful procedures in surgery. In Germany there is a great variety of cemented and uncemented implants with different principles of fixation. We reviewed the different principles, with particular reference to long-term clinical outcome, and discuss the most popular systems available in Germany. Despite many new developments which have been made in the field of cementless hip replacement, cemented total hip arthroplasty will remain the "gold standard" until prospective long-term data (> 15 years) of cementless systems become available.