Quantitative and individualized assessment of the learning curve in preoperative planning of the acetabular cup size in primary total hip arthroplasty.

INTRODUCTION: The aim of the present study was to investigate the learning curves of 2 trainees with different experience levels to reach proficiency in preoperative planning of the cup size based on learning curve cumulative summation (LC-CUSUM) statistics and a cumulative summation (CUSUM) test. MATERIALS AND METHODS: One-hundred-twenty patients who had undergone primary total hip arthroplasty with a cementless cup were selected. Preoperative planning was performed by an experienced orthopedic surgeon. Trainee 1 (student) and trainee 2 (resident) planned the cup size. The trainees were blinded to the preoperative plan and the definitive cup size. Only after a cup size was chosen, the trainees were unblinded to the preoperative plan of the surgeon. LC-CUSUM was applied to both trainees to determine when proficiency in determining the appropriate cup size was reached. A CUSUM test was applied to ensure retention of proficiency. RESULTS: With reference to the preoperative plan of the surgeon, LC-CUSUM indicated proficiency after 94 planning attempts for trainee 1 and proficiency after 66 attempts for trainee 2, respectively. Trainee 1 and 2 maintained proficiency thereafter. With reference to the definitive cup size, LC-CUSUM did not signal competency within the first 120 planning attempts for trainee 1. Trainee 2 was declared competent after 103 attempts and retained competency thereafter. CONCLUSIONS: LC-CUSUM/CUSUM allow for an individualized, quantitative and continuous assessment of planning quality. Based on LC-CUSUM statistics, the two trainees of this study gain proficiency in planning of the acetabular cup size after 50-100 attempts when an immediate feedback is provided. Previous experience positively influences the performance. The study serves as basis for the medical education of students and residents in joint replacement procedures.

Are there clinically relevant anatomical differences of the proximal femur in patients with mild dysplastic and primary hip osteoarthritis? A CT-based matched-pairs cohort study.

AIM: To investigate the three-dimensional anatomy and shape of the proximal femur, comparing patients with secondary osteoarthritis (OA) due to mild developmental dysplasia of the hip (DDH) and primary hip OA. MATERIALS AND METHODS: This retrospective radiographic computed tomography (CT)-based study investigated proximal femoral anatomy in a consecutive series of 84 patients with secondary hip OA due to mild DDH (Crowe type I&II/Hartofilakidis A) compared to 84 patients with primary hip OA, matched for gender, age at surgery, and body mass index. RESULTS: Men with DDH showed higher neck shaft angles (127±5° vs. 123±4°; p<0.001), whereas women with DDH had a larger femoral head diameter (46±4 vs. 44±3 mm; p=0.002), smaller femoral offset (36±5 vs. 40±4 mm; p<0.001), decreased leg torsion (25±13° vs. 31±16°; p=0.037), and a higher neck shaft angle (128±7° vs. 123±4°; p<0.001) compared to primary OA patients. Similar patterns of the three-dimensional endosteal canal shape of the proximal femur, but a high inter-individual variability for femoral canal torsion at the meta-diaphyseal level were found for DDH and primary OA patients. CONCLUSION: Standard cementless stem designs are suitable to treat patients with secondary hip OA due to mild DDH; however, high patient variability and subtle anatomical differences in the proximal femur should be respected.

Unicondylar knee arthroplasty using cobalt-chromium implants in patients with self-reported cutaneous metal hypersensitivity.

AIMS: The treatment of patients with allergies to metal in total joint arthroplasty is an ongoing debate. Possibilities include the use of hypoallergenic prostheses, as well as the use of standard cobalt-chromium (CoCr) alloy. This non-designer study was performed to evaluate the clinical outcome and survival rates of unicondylar knee arthroplasty (UKA) using a standard CoCr alloy in patients reporting signs of a hypersensitivity to metal. PATIENTS AND METHODS: A consecutive series of patients suitable for UKA were screened for symptoms of metal hypersensitivity by use of a questionnaire. A total of 82 patients out of 1737 patients suitable for medial UKA reporting cutaneous metal hypersensitivity to cobalt, chromium, or nickel were included into this study and prospectively evaluated to determine the functional outcome, possible signs of hypersensitivity, and short-term survivorship at a minimum follow-up of 1.5 years. RESULTS: At a mean follow-up of three years (1.5 to 5.7), no local or systemic symptoms of hypersensitivity to metal were observed. One patient underwent revision surgery to a bicondylar prosthesis due to a tibial periprosthetic fracture resulting in a survival rate of 98.8% (95% confidence interval (CI) 91.7 to 99.8; number at risk, 28) at three years with the endpoint of revision for any reason and a survival rate of 97.6% (95% CI 90.6 to 99.3; number at risk, 29) for the endpoint of all reoperations. Clinical outcome was good to excellent with a mean Oxford Knee Score of 42.5 (sd 2.5; 37 to 48). CONCLUSION: This study is the first demonstrating clinical results and survival analysis of UKA using a CoCr alloy in patients with a history of metal hypersensitivity. Functional outcome and survivorship are on a high-level equivalent to those reported for UKA in patients without a history of metal hypersensitivity. No serious local or systemic symptoms of metal hypersensitivity could be detected, and no revision surgery was performed due to an adverse reaction to metal ions.

Mid-term results of lateral unicondylar mobile bearing knee arthroplasty: a multicentre study of 363 cases.

AIMS: The aim of this independent multicentre study was to assess the mid-term results of mobile bearing unicondylar knee arthroplasty (UKA) for isolated lateral osteoarthritis of the knee joint. PATIENTS AND METHODS: We retrospectively evaluated 363 consecutive, lateral UKAs (346 patients) performed using the Oxford domed lateral prosthesis undertaken in three high-volume knee arthroplasty centres between 2006 and 2014. Mean age of the patients at surgery was 65 years (36 to 88) with a mean final follow-up of 37 months (12 to 93) RESULTS: A total of 36 (10.5%) patients underwent revision surgery, giving a survival rate of 90.1% at three years (95% confidence intervals (CI) 86.1 to 93.1; number at risk: 155) and 85.0% at five years (95% CI 77.9 to 89.9; number at risk: 43). Dislocation of the mobile bearing occurred in 18 patients (5.6%) at three years (95% CI 1.0 to 16.4; number at risk: 154) and in 20 patients (8.5%) at five years (95% CI 1.0 to 27.0; number at risk: 42). There were no significant differences in the dislocation rate between the participating centres or the surgeons. We were not able to identify an effect of each surgeon's learning curve on the dislocation rate of the mobile bearing. The clinical outcome in patients without revision surgery at final follow-up was good to excellent, with a mean Oxford knee score of 40.3 (95% CI 39.4 to 41.2), a mean Tegner activity score of 3.2 (95% CI 3.1 to 3.3) and a mean University of California, Los Angeles score of 5.7 (95% CI 5.5 to 5.9). CONCLUSION: Our data, which consists of a high number of patients treated with mobile bearing UKA in the lateral compartment, indicates a high revision rate of 15% at five years with dislocation of the mobile bearing being the main reason for implant failure. Despite the good functional and clinical results and the high patient satisfaction in our study group, we therefore discontinued using mobile-bearing lateral UKA in favour of a fixed-bearing component. Cite this article: Bone Joint J 2018;100-B:42-9.

[Lateral unicompartmental knee arthroplasty - a challenge]. / Die laterale Schlittenprothese ­ eine Herausforderung.

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%.

[Indications and Borderline Indications for Medial Mobile Bearing Unicondylar Knee Replacement]. / Indikationen und Grenzindikationen zum medialen unikondylären Gelenkersatz mit mobiler Inlay-Komponente.

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.

[Tips and Tricks for Mobile Bearing Medial Unicondylar Knee Replacement]. / Tipps und Tricks zur Implantation der medialen unikondylären Mobile-Bearing-Schlittenprothese.

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.

[Experiences with lateral unicondylar prostheses]. / Erfahrungen mit lateralen unikondylären Prothesen.

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.

How many different types of femora are there in primary hip osteoarthritis? An active shape modeling study.

We assessed the variation in proximal femoral canal shape and its association with geometric and demographic parameters in primary hip OA. In a retrospective cohort study, the joint geometry of the proximal femur was evaluated on radiographs and corresponding CT scans of 345 consecutive patients with end-stage hip OA. Active shape modeling (ASM) was performed to assess the variation in endosteal shape of the proximal femur. To identify natural groupings of patients, hierarchical cluster analysis of the shape modes was used. ASM identified 10 independent shape modes accounting for >96% of the variation in proximal femoral canal shape within the dataset. Cluster analysis revealed 10 specific shape clusters. Significant differences in geometric and demographic parameters between the clusters were observed. ASM and subsequent cluster analysis have the potential to identify specific morphological patterns of the proximal femur despite the variability in proximal femoral anatomy. The study identified patterns of proximal femoral canal shape in hip OA that allow a comprehensive classification of variation in shape and its association with joint geometry. Our data may improve future stem designs that will optimize stem fit and simultaneously allow individual restoration of hip biomechanics.

Prediction of three-dimensional femoral offset from AP pelvis radiographs in primary hip osteoarthritis.

BACKGROUND: In pre-operative planning for total hip arthroplasty (THA), femoral offset (FO) is frequently underestimated on AP pelvis radiographs as a result of inaccurate patient positioning, imprecise magnification, and radiographic beam divergence. The aim of the present study was to evaluate the accuracy and reliability of predicting three-dimensional (3-D) FO from standardised AP pelvis radiographs. METHODS: In a retrospective cohort study, pre-operative AP pelvis radiographs, AP hip radiographs and CT scans of a consecutive series of 345 patients (345 hips, 146 males, 199 females, mean age 60 (range: 40-79) years, mean body-mass-index 27 (range: 19-57)kg/m(2)) with primary end-stage hip OA were reviewed. Patients were positioned according to a standardised protocol and all images were calibrated. Using validated custom programmes, FO was measured on corresponding radiographs and CT scans. Measurement reliability was evaluated using intra-class-correlation-coefficients. To predict 3-D FO from AP pelvis measurements and to assess the accuracy compared to CT, the entire cohort was randomly split into subgroups A and B. Gender specific regression equations were derived from group A (245 patients) and the accuracy of prediction was evaluated in group B (100 patients) using Bland-Altman plots. RESULTS: In the entire cohort, mean FO was 39.2mm (95%CI: 38.5-40.0mm) on AP pelvis radiographs, 44.1mm (95%CI: 43.4-44.9mm) on AP hip radiographs and 44.6mm (95%CI: 44.0-45.2mm) on CT scans. In group B, we observed no significant difference between gender specific predicted FO (males: 48.0mm, 95%CI: 47.1-48.8mm; females: 42.0mm, 95%CI: 41.1-42.8mm) and FO as measured on CT (males: 47.7mm, 95%CI: 46.1-49.4mm, p=0.689; females: 41.6mm, 95%CI: 40.3-43.0mm, p=0.607). CONCLUSIONS: The present study suggests that FO can be accurately and reliably predicted from AP pelvis radiographs in patients with primary end-stage hip osteoarthritis. Our findings support the surgeon in pre-operative templating on AP-pelvis radiographs and may improve offset and limb length restoration in THA without the routine performance of additional radiographs or CT.

In vivo serum titanium ion levels following modular neck total hip arthroplasty--10 year results in 67 patients.

The objective of the present cross-sectional study was to determine in vivo titanium ion levels following cementless total hip arthroplasty (THA) using a modular stem system with different shapes for femoral canal fit and multiple neck options. A consecutive series of 173 patients (190 hips) who underwent cementless modular neck THA and a ceramic on polyethylene bearing with a median follow-up of 9 (7-13) years was evaluated retrospectively. According to a standardized protocol, titanium ion measurements were performed on 67 patients using high-resolution inductively coupled plasma-mass spectrometry. Ion levels were compared to a control group comprising patients with non-modular titanium implants (n=11) and to individuals without implants (n=23). Modular neck THA did not result in elevated titanium ion levels compared to non-modular THA. Compared to individuals without implants, both modular THA and non-modular THA showed elevated titanium ion levels. Absolute titanium ion levels, however, were comparatively low for both implants. The data suggest that the present modular stem system does not result in elevated systemic titanium ion levels in the medium term when compared to non-modular stems. Further longitudinal studies are needed to evaluate the use of systemic titanium ion levels as an objective diagnostic tool to identify THA failure and to monitor patients following revision surgery.

Mobile-bearing lateral unicompartmental knee replacement with the Oxford domed tibial component: an independent series.

The Oxford mobile-bearing unicompartmental knee replacement (UKR) is an effective and safe treatment for osteoarthritis of the medial compartment. The results in the lateral compartment have been disappointing due to a high early rate of dislocation of the bearing. A series using a newly designed domed tibial component is reported. The first 50 consecutive domed lateral Oxford UKRs in 50 patients with a mean follow-up of three years (2.0 to 4.3) were included. Clinical scores were obtained prospectively and Kaplan-Meier survival analysis was performed for different endpoints. Radiological variables related to the position and alignment of the components were measured. One patient died and none was lost to follow-up. The cumulative incidence of dislocation was 6.2% (95% confidence interval (CI) 2.0 to 17.9) at three years. Survival using revision for any reason and aseptic revision was 94% (95% CI 82 to 98) and 96% (95% CI 85 to 99) at three years, respectively. Outcome scores, visual analogue scale for pain and maximum knee flexion showed a significant improvement (p < 0.001). The mean Oxford knee score was 43 (SD 5.3), the mean Objective American Knee Society score was 91 (SD 13.9) and the mean Functional American Knee Society score was 90 (SD 17.5). The mean maximum flexion was 127° (90° to 145°). Significant elevation of the lateral joint line as measured by the proximal tibial varus angle (p = 0.04) was evident in the dislocation group when compared with the non-dislocation group. Clinical results are excellent and short-term survival has improved when compared with earlier series. The risk of dislocation remains higher using a mobile-bearing UKR in the lateral compartment when compared with the medial compartment. Patients should be informed about this complication. To avoid dislocations, care must be taken not to elevate the lateral joint line.

Femoral offset is underestimated on anteroposterior radiographs of the pelvis but accurately assessed on anteroposterior radiographs of the hip.

The aim of this retrospective cohort study was to identify any difference in femoral offset as measured on pre-operative anteroposterior (AP) radiographs of the pelvis, AP radiographs of the hip and corresponding CT scans in a consecutive series of 100 patients with primary end-stage osteoarthritis of the hip (43 men and 57 women with a mean age of 61 years (45 to 74) and a mean body mass index of 28 kg/m(2) (20 to 45)). Patients were positioned according to a standardised protocol to achieve reproducible projection and all images were calibrated. Inter- and intra-observer reliability was evaluated and agreement between methods was assessed using Bland-Altman plots. In the entire cohort, the mean femoral offset was 39.0 mm (95% confidence interval (CI) 37.4 to 40.6) on radiographs of the pelvis, 44.0 mm (95% CI 42.4 to 45.6) on radiographs of the hip and 44.7 mm (95% CI 43.5 to 45.9) on CT scans. AP radiographs of the pelvis underestimated femoral offset by 13% when compared with CT (p < 0.001). No difference in mean femoral offset was seen between AP radiographs of the hip and CT (p = 0.191). Our results suggest that femoral offset is significantly underestimated on AP radiographs of the pelvis but can be reliably and accurately assessed on AP radiographs of the hip in patients with primary end-stage hip osteoarthritis. We, therefore, recommend that additional AP radiographs of the hip are obtained routinely for the pre-operative assessment of femoral offset when templating before total hip replacement.

Late peri-prosthetic femoral fracture as a major mode of failure in uncemented primary hip replacement.

Peri-prosthetic femoral fracture after total hip replacement (THR) is associated with a poor outcome and high mortality. However, little is known about its long-term incidence after uncemented THR. We retrospectively reviewed a consecutive series of 326 patients (354 hips) who had received a CLS Spotorno replacement with an uncemented, straight, collarless tapered titanium stem between January 1985 and December 1989. The mean follow-up was 17 years (15 to 20). The occurrence of peri-prosthetic femoral fracture during follow-up was noted. Kaplan-Meier survival analysis was used to estimate the cumulative incidence of fracture. At the last follow-up, 86 patients (89 hips) had died and eight patients (eight hips) had been lost to follow-up. A total of 14 fractures in 14 patients had occurred. In ten hips, the femoral component had to be revised and in four the fracture was treated by open reduction and internal fixation. The cumulative incidence of peri-prosthetic femoral fracture was 1.6% (95% confidence interval 0.7 to 3.8) at ten years and 4.5% (95% confidence interval 2.6 to 8.0) at 17 years after the primary THR. There was no association between the occurrence of fracture and gender or age at the time of the primary replacement. Our findings indicate that peri-prosthetic femoral fracture is a significant mode of failure in the long term after the insertion of an uncemented CLS Spotorno stem. Revision rates for this fracture rise in the second decade. Further research is required to investigate the risk factors involved in the occurrence of late peri-prosthetic femoral fracture after the implantation of any uncemented stem, and to assess possible methods of prevention.

Bone remodeling around stable uncemented titanium stems during the second decade after total hip arthroplasty: a DXA study at 12 and 17 years.

UNLABELLED: In a cohort study, bone mineral density (BMD) around uncemented femoral components after total hip arthroplasty (THA) was evaluated. The results suggest that there are no clinically relevant changes in overall periprosthetic BMD in the second decade. However, continuous remodeling with limited proximal bone loss (stress-shielding) occurs, predominantly in female patients. INTRODUCTION: Progressive periprosthetic bone loss and stress-shielding are a major concern in THA. Little is known about the extent and pattern of periprosthetic bone remodeling around uncemented stems in the second decade. METHODS: In a cohort study, periprosthetic BMD was measured in 131 patients with 146 uncemented CLS stems using dual-energy X-ray absorptiometry (DXA) at a mean of 12 years postoperatively (t1). Patients were followed clinically and radiographically, and a second DXA was performed at a mean of 17 years postoperatively (t2) using the identical protocol. RESULTS: We obtained a complete set of two consecutive DXA measurements for 88 hips (78 patients, 35 male, 43 female). On radiographic evaluation at t1 and t2, regular bone ongrowth was present in all cases and no signs of radiographic loosening, severe bone loss or diaphyseal cortical hypertrophy were detected. There was no clinically relevant change in overall periprosthetic BMD (netavg) between t1 and t2 for both male and female patients. We analyzed the differences in BMD in the periprosthetic regions of interest (ROIs) according to Gruen and found a slight decrease in periprosthetic BMD in ROI 7 in male patients and in ROIs 1, 4, 6 and 7 in female patients. CONCLUSIONS: The study suggests that there are no clinically relevant changes in overall periprosthetic BMD around stable, straight uncemented stems between 12 and 17 years postoperatively. However, continuous remodeling with limited proximal bone loss occurs, predominantly in female patients. After secondary osteointegration of this implant, stress-shielding remains minimal in the second decade.

[Comparison of short-term results after CUP prosthesis with cemented glenoid components and total shoulder arthroplasty: a matched-pair analysis]. / Die CUP-Prothese mit einer zementierten Schultergelenkpfanne im Vergleich zur konventionellen anatomischen Totalendoprothese - eine Matched-Pair-Analyse.

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.

[Long-term results of uncemented stems in total hip arthroplasty: analysis of survival rates with a minimum 15-year follow-up]. / Langzeitergebnisse zementfreier Hüftendoprothesenschäfte: Analyse der Uberlebensraten mit einem Nachuntersuchungszeitraum von mindestens 15 Jahren.

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.

Periprosthetic tibial fractures in unicompartmental knee arthroplasty as a function of extended sagittal saw cuts: an experimental study.

Periprosthetic tibial plateau fractures (TPF) are rare but represent a serious complication of unicompartmental knee arthroplasty (UKA). As TPFs usually occur perioperatively, these can be associated with extended sagittal saw cuts during surgery. The aim of the study was to evaluate TPF as a function of extended sagittal saw cuts. The hypothesis was that extended sagittal saw cuts reduce the loading capacity of the tibial plateau and increase the risk of periprosthetic TPF. In a randomised study, standardised cemented Oxford UKA tibial component implantation was performed in six matched, paired fresh-frozen tibiae. In group A, a regular preparation of the tibial plateau was performed, whereas in group B a standardised extended sagittal saw cut was made at the dorsal cortex of the tibia. All tibiae were fractured under standardised conditions and fracture patterns and fracture loads were analysed. In group A, tibiae fractured with a mean load of F(max)=3.9 (2.3-8.5) kN, whereas in group B fractures occurred at a mean load of F(max)=2.6 (1.1-5.0) kN. The difference was statistically significant (p<0.05). Extended sagittal saw cuts in UKA weaken the tibial bone structure. Our results show that descendent extended sagittal saw cuts of 10 degrees reduce fracture loads by about 30%. Surgeons should be aware of the potential pitfalls of an extended sagittal saw cut, as this can lead to reduced loading capacity of the tibial plateau and increase the risk of periprosthetic TPF.

Humeral head resurfacing for fixed anterior glenohumeral dislocation.

The purpose of this prospective study was to describe cementless humeral surface replacement arthroplasty (CHSRA) as a bone preserving treatment option for patients with fixed anterior glenohumeral dislocation. Ten patients with post-traumatic fixed anterior glenohumeral dislocation underwent CHSRA with a mean follow-up of 24 months. All patients were evaluated clinically using the Constant score and with radiographs in two planes. There were two reoperations: one patient developed glenoid erosion and was revised and in another case redislocation occurred. Clinical or radiographical signs of implant loosening were not found. The humeral head centred in the glenoid in nine out of ten cases radiographically. The Constant score increased from 20 points preoperatively to 61 points postoperatively (p < 0.007). CHSRA is a viable treatment option for elderly patients with fixed anterior glenohumeral dislocation and bone defects of the humeral head. Good clinical results and a moderate complication rate were found in the short term.

[Acetabular reinforcement rings in revision total hip arthroplasty: midterm results in 298 cases]. / Abstützschalen in der Revisionsendoprothetik der Hüfte : Mittelfristige Ergebnisse von 298 Implantaten.

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.