Risk for total knee arthroplasty after tibial plateau fractures: a systematic review.

PURPOSE: Tibial plateau fractures (TPFs) may lead to posttraumatic osteoarthritis and increase the risk for total knee arthroplasty (TKA). The aim of this systematic review was to analyse the conversion rate to TKA after TPF treatment. METHODS: A systematic search for studies reviewing the conversion rate to TKA after TPF treatment was conducted. The studies were screened and assessed by two independent observers. The conversion rate was analysed overall and for selected subgroups, including different follow-up times, treatment methods, and study sizes. RESULTS: A total of forty-two eligible studies including 52,577 patients were included in this systematic review. The overall conversion rate of treated TPF to TKA in all studies was 5.1%. Thirty-eight of the forty-two included studies indicated a conversion rate under 10%. Four studies reported a higher percentage, namely, 10.8%, 10.9%, 15.5%, and 21.9%. Risk factors for TKA following TPF treatment were female sex, age, and low surgeon and hospital volume. The conversion rate to TKA is particularly high in the first 5 years after fracture. CONCLUSION: Based on the studies, it can be assumed that the conversion rate to TKA is approximately 5%. The risk for TKA is manageable in clinical practice. PROSPERO REGISTRATION NUMBER: CRD42023385311. LEVEL OF EVIDENCE: IV.

No component loosening of a cementless deep dish rotating platform knee at a 5-year follow-up.

PURPOSE: Cemented fixation remains the gold standard in total knee arthroplasty. With an increasing number of younger patients undergoing total knee arthroplasty and a growing patient population demanding higher physical activity, a rising interest in discussion of cementless fixation is notable. The current scientific literature does not give a clear recommendation for or against uncemented total knee arthroplasty. The purpose of this study was the investigation of the 5-year clinical and radiographic outcomes of a cementless deep-dish rotating platform implant. METHODS: A total of 91 primary cementless total knee arthroplasties were included in this single-centre prospective observational study. The primary outcome was revision rate due to aseptic component loosening. Further outcome measures were assessment of the of the radiographic outcome as well as the clinical outcome based on Range of Motion and scores such as American Knee Society Score, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score and European Quality of Life 5 Dimension 3 Level at a follow-up of 5 years. RESULTS: Mean age of the study population was 67.3 ± 6.6 years with 49.5% of the participants being female. Aseptic component loosening occurred in none of the patients. Implant survival with revision for any reason as endpoint was 97.8% (95% CI 100-96%) and 95.6% (95% CI 100-94%) with reoperation of any cause as endpoint. Radiolucent lines were detected in a total of eight cases (8.8%) and disappeared within the first year after surgery in five cases. Total Range of Motion improved significantly from 106° ± 15° preoperatively to 118° ± 10° at final FU (p < 0.001). All investigated scores improved significantly after total knee arthroplasty. CONCLUSION: The results of this study reveal excellent mid-term performance of a cementless deep dish rotating platform total knee implant, with no component loosening, very low overall revision rate, only temporarily present radiolucent lines in a minority of patients and excellent clinical results. Therefore, cementless total knee arthroplasty is an appropriate treatment option for patients with severe osteoarthritis of the knee. LEVEL OF EVIDENCE: Level II (prospective cohort study).

Complication rates after proximal femoral nailing: does level of training matter?

BACKGROUND: Surgical treatment of pertrochanteric fractures is one of the most performed surgeries in orthogeriatrics. Proximal femoral nailing, the most performed procedure, is often used as a training surgery for young residents. The objective of this study was to evaluate the relevance of the resident's training level to complication rates. MATERIAL AND METHODS: This study was a retrospective cohort study. Surgeons were divided into four groups according to their training level. Complications included infection, cut-out, and revision surgery. The study was performed at a level 1 trauma center. All patients who were treated with proximal femoral nailing surgery with a radiological follow-up of at least 3 months were included. RESULTS: Of the 955 patients extracted, a total of 564 patients met the inclusion criteria. Second-year residents had significantly higher cut-out rates (p = 0.012). Further analysis indicated a correlation between level of training and surgery duration (p < 0.001) as well as a correlation between surgery duration and infection rate (p < 0.001). The overall complication rate was 11.2%. Analyzing overall complications, no significant difference was found when comparing surgeon groups (p = 0.3). No statistically significant difference was found concerning infection (p = 0.6), cut-out (p = 0.7), and revision surgery (p = 0.3) either. CONCLUSION: Complication rates after proximal femoral nailing are not higher in patients who are treated by residents. Therefore, proximal femoral nailing is an excellent procedure for general orthopedic training. However, we must keep in mind that accurate positioning of the femoral neck screw is essential to keep cut-out rates as low as possible.

Results after spica cast immobilization following hip reconstruction in 95 cases: is there a need for alternative techniques?

INTRODUCTION: Developmental dysplasia of the hip (DDH), neurogenic dysplasia of the hip (NDH), and Perthes disease often require surgical treatment. Spica casting is a common postoperative immobilization. The purpose of this study was to evaluate the complications related to the immobilization. MATERIALS AND METHODS: In a retrospective analysis, we included 83 patients (95 hips), who underwent hip reconstructive surgery between 2008 and 2018. We had 43 female and 40 male patients. Age reached from 3 months to 19 years. All patients were treated with a spica cast postoperatively for a 6-week protocol. Complications were analyzed using the full medical documentation and classified according to Clavien-Dindo. RESULTS: We had complications in 23 patients (27.7%). We counted superficial skin lesions in seven, deep skin lesions in three, spasticity of adductors in three, subluxation in two, infection of the plate in one, fracture of the plate in one, compliance problem in one, dislocations of the cast in two, reluxation in one, delayed bone healing in one and spasticity of knee flexors in one case. According to the classification of Clavien-Dindo, we were able to count ten type I, four type II, nine type III, zero type IV and zero type V adverse events. CONCLUSION: The usage of a spica cast after hip reconstructive surgery is still the most popular way of aftertreatment. It has a low complication rate, which may be lowered by well-applied casts and foam padding. Known complications such as spasticity in patients with cerebral palsy, skin lesions, and pressure sores should be observed and avoided. Shorter protocols for immobilization with the usage of foam padding and foam splints lead to less complications. CLINICAL RELEVANCE: Evidence level level IV, case series.

Intermediate to long-term clinical outcomes and survival analysis of the Salto Mobile Bearing total ankle prothesis.

INTRODUCTION: Osteoarthritis of the ankle is a major burden to affected patients. While tibio-talar arthrodesis has been the gold-standard regarding the treatment of osteoarthritis of the ankle joint for many years, at present total ankle arthroplasty (TAA) provides appealing clinical outcomes and is continually gaining popularity. The aim of this study was to evaluate the intermediate- to long-term clinical outcome including the survival rate of Salto Mobile Bearing TAA (Tonier SA, Saint Ismier, France). MATERIAL AND METHODS: In this retrospective study intermediate- to long-term outcomes measures [Ankle Range of Motion (ROM), American Orthopaedic Foot and Ankle Score (AOFAS score) and survival rate] of 171 consecutive TAA were analysed and compared before and after surgery. Revision was defined as secondary surgery with prothesis component removal, while reoperation was defined as a non-revisional secondary surgery involving the ankle. RESULTS: At a mean follow-up (FU) period of 7.2 ± 2.7 years (range 2.0 to 14.1 years) there was a significant improvement in ankle ROM (total ROM improved from 25.0° ± 15.0° to 28.7° ± 11.3°, p = 0.015; plantarflexion improved from 18.4° ± 11.7° to 20.6° ± 8.2°, p = 0.044; dorsiflexion improved from 6.6° ± 5.7° to 8.1° ± 4.9°, p = 0.011). AOFAS score increased significantly by 41 ± 15 points after surgery (43.3 ± 11.1 before and 84.3 ± 12.0 after surgery, p < 0.001). Overall survival rate within the FU was 81.3% (95% CI 75.3% to 87.3%) with any secondary surgery, 89.9% (95% CI 84.1% to 93.6%) with revision and 93.6% (95% CI 89.8% to 97.3%) with reoperation as endpoint. CONCLUSION: This study endorses the previously reported appealing intermediate- to long-term outcomes of the Salto Mobile Bearing TAA. There was a significant increase in ROM and AOFAS score as well as decent implant survival at final FU.

Coccygectomy for coccygodynia: a cohort study with a long-term follow-up of up to 29 years.

PURPOSE: We aim to critically review the effectiveness and safety of coccygectomy with special regard to long-term outcomes. METHODS: Coccygectomy was performed in our clinic in 38 patients between 1990 and 2019. All these patients (32 females vs. 6 males) have failed to respond to conservative treatment for at least 6 months prior to surgery. All patients were available for follow-up after mean 12,3 years (2 months to 29 years, 11 patients had a minimum FUP of 24 years). We evaluated all patients clinically and radiologically. RESULTS: Nineteen patients reported traumatic and 17 patients reported idiopathic onset of their symptoms; one patient had clinical symptoms after childbirth and another patient had coccygodynia after extensive low back surgery. 36 of our 38 patients were free of pain at least 6 months after surgery and had good or excellent clinical results according to the VAS which improved from 6.37 (SD 1.08) preoperatively to 0.68 (SD 0.99) at the recent follow-up. Two patients showed an ODI > 22 at the recent follow-up (24 and 28) and 32 had an ODI equal or under 4. There was no statistical significant difference in terms of clinical outcome between the different radiological types of the coccyx. Postoperative complications were rare: 1 superficial infection and one re-operation 6 months after initial surgery due to an pre-existing exostosis which had not been removed at the index surgery; no neurological complications and no major bleeding occurred. No patient had recurrent onset of coccygodynia. 37 out of 38 patients would have coccygectomy again. CONCLUSIONS: Coccygectomy is a safe treatment option in patients with coccygodynia and shows excellent long-term results. We recommend to perform coccygectomy if patients fail to respond to conservative treatment for 6 months. LEVEL OF EVIDENCE: IV.

A predominant Th1 polarization is present in synovial fluid of end-stage osteoarthritic knee joints: analysis of peripheral blood, synovial fluid and synovial membrane.

Thorough understanding of the complex pathophysiology of osteoarthritis (OA) is necessary in order to open new avenues for treatment. The aim of this study was to characterize the CD4+ T cell population and evaluate their activation and polarization status in OA joints. Fifty-five patients with end-stage knee OA (Kellgren-Lawrence grades III-IV) who underwent surgery for total knee arthroplasty (TKA) were enrolled into this study. Matched samples of synovial membrane (SM), synovial fluid (SF) and peripheral blood (PB) were analysed for CD3+ CD4+ CD8- T cell subsets [T helper type 1 (Th1), Th2, Th17, regulatory T cells] and activation status (CD25, CD69, CD45RO, CD45RA, CD62L) by flow cytometry. Subset-specific cytokines were analysed by cytometric bead array (CBA). SM and SF samples showed a distinct infiltration pattern of CD4+ T cells. In comparison to PB, a higher amount of joint-derived T cells was polarized into CD3+ CD4+ CD8- T cell subsets, with the most significant increase for proinflammatory Th1 cells in SF. CBA analysis revealed significantly increased immunomodulating cytokines [interferon (IFN)-γ, interleukin (IL)-2 and IL-10] in SF compared to PB. Whereas in PB only a small proportion of CD4+ T cells were activated, the majority of joint-derived CD4+ T cells can be characterized as activated effector memory cells (CD69+ CD45RO+ CD62L- ). End-stage OA knees are characterized by an increased CD4+ T cell polarization towards activated Th1 cells and cytokine secretion compared to PB. This local inflammation may contribute to disease aggravation and eventually perpetuate the disease process.

Unicompartmental and bicompartmental knee osteoarthritis show different patterns of mononuclear cell infiltration and cytokine release in the affected joints.

It is still controversial which cell types are responsible for synovial inflammation in osteoarthritic (OA) joints. The aim of this study was to quantify the mononuclear cell populations and their cytokines in patients with different knee OA subtypes. Synovial membrane (SM), synovial fluid (SF) and peripheral blood (PB) were harvested from patients with unicompartmental (UC) and bicompartmental (BC) knee OA. Frequencies of mononuclear cells were assessed by flow cytometry in PB and SM. Naive SF samples were analysed for a broad variety of cytokines by multiplex analysis. SM of both groups displayed a distinct mononuclear cell infiltration, with CD14(+) macrophages being the major cell population, followed by CD4(+) T cells and only small numbers of CD8(+) T, CD19(+) B and CD16(+) CD56(+) natural killer (NK) cells. Between the two groups, SM of BC OA showed significantly higher amounts of mononuclear cells (135·7 ± 180 versus 805 ± 675 cells/mg, P = 0·0009) and higher CD4(+) T cell presence (3·4 ± 4·6 versus 9·1 ± 7·5%, P = 0·0267). SF of BC OA displayed significantly higher concentrations for a number of proinflammatory cytokines [CXCL1, eotaxin, interferon (IFN)-γ, interleukin (IL)-7, IL-8, IL-9, IL-12]. UC and BC OA show significant differences in their synovial inflammatory pattern. Whereas in UC OA CD14(+) macrophages are the predominant cell population, BC OA has a higher inflammatory profile and seems to be driven by CD14(+) macrophages and CD4(+) T cells. Inclusion of clinical information into the analysis of cellular and molecular results is pivotal in understanding the pathophysiology of OA.

[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.

The influence of bone marrow- and synovium-derived mesenchymal stromal cells from osteoarthritis patients on regulatory T cells in co-culture.

There is increasing evidence that inflammation in the synovium plays a major role in the progression of osteoarthritis (OA). However, the immunogenic properties of mesenchymal stromal cells (MSCs), which are considered to regulate immunity in various diseases, remain largely unknown in OA. The purpose of this study was to determine the influence of MSCs from OA patients on regulatory T cells (Tregs ) in an allogeneic co-culture model. Bone marrow (BM) and synovial membrane (SM) were harvested from hip joints of OA patients and co-cultured with lymphocytes enriched in CD4(+) CD25(+) CD127(-) regulatory T cells (Treg (+) LC) from healthy donors. Treg proportions and MSC markers were assessed by flow cytometry. Cytokine levels were assessed after 2 and 5 days of co-cultivation. Additionally, Treg (+) LC cultures were analysed in the presence of interleukin (IL)-6 and MSC-supernatant complemented medium. B-MSCs and S-MSCs were able to retain the Treg proportion compared to lymphocyte monocultures. T cell-MSC co-cultures showed a significant increase of IL-6 compared to MSC cultures. S-MSCs produced higher amounts of IL-6 compared to B-MSCs, both in single and T cell co-cultures. The effect of retaining the Treg percentage could be reproduced partially by IL-6 addition to the medium, but could only be observed fully when using MSC culture supernatants. Our data demonstrate that retaining the Treg phenotype in MSC-T cell co-cultures can be mediated by MSC derived from OA patients. IL-6 plays an important role in mediating these processes. To our knowledge, this study is the first describing the interaction of MSCs from OA patients and Tregs in an allogeneic co-culture model.

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.

Straight stem and threaded cup in patients under 60 years of age: 28.8-30.2 years of follow-up.

PURPOSE: The aim of this retrospective observational study of one cohort was to evaluate the long-term outcome in patients younger than 60 years after total hip arthroplasty using a straight uncemented stem and an uncemented threaded cup. METHODS: Between 1986 and 1987, 75 hips of 75 patients (mean age, 53.35 ± 6.17 years) were consecutively implanted with an Alloclassic Zweymüller/Alloclassic SL stem and an Alloclassic CSF cup. Forty-four patients had died over the last 30 years. The remaining 31 patients (mean age, 82.9 ± 6.4 years) were reinvited for follow-up examinations. Clinical and radiographic evaluations were carried out. RESULTS: At a mean follow-up of 29.5 (28.8-30.2), 4 patients (5.3%) were lost to follow-up. For the endpoint aseptic loosening (defined as the removal of stem or the cup for 2 cases), the overall survival rate is 97.3%. For the endpoint revision for any reason (22 patients), the survival rate is 70.6%. Eleven patients needed an exchange of head and liner, caused by wear. The average time from implantation until change of head and liner was 21.44 years (SD 5.92). Other reasons for revision surgery were septic loosening (3 cases), aseptic loosening of stem and cup (1 case), aseptic loosening of stem (1 case), periprosthetic calcification (2 cases), implant fracture (1 case), periprosthetic fracture (1 case), intraoperative fissure of stem (1 case), and total wear of liner including cup (1 case). CONCLUSION: The combination of a straight stem (Alloclassic) and a screw cup (CSF) shows excellent results in young patients under the age of 60 at ultra-long-term follow-up at 30 years. Revisions due to wear of the polyethylene liner are more likely than in the older patients.

Can spinopelvic mobility be predicted in patients awaiting total hip arthroplasty? A prospective, diagnostic study of patients with end-stage hip osteoarthritis.

AIMS: This study of patients with osteoarthritis (OA) of the hip aimed to: 1) characterize the contribution of the hip, spinopelvic complex, and lumbar spine when moving from the standing to the sitting position; 2) assess whether abnormal spinopelvic mobility is associated with worse symptoms; and 3) identify whether spinopelvic mobility can be predicted from static anatomical radiological parameters. PATIENTS AND METHODS: A total of 122 patients with end-stage OA of the hip awaiting total hip arthroplasty (THA) were prospectively studied. Patient-reported outcome measures (PROMs; Oxford Hip Score, Oswestry Disability Index, and Veterans RAND 12-Item Health Survey Score) and clinical data were collected. Sagittal spinopelvic mobility was calculated as the change from the standing to sitting position using the lumbar lordosis angle (LL), sacral slope (SS), pelvic tilt (PT), pelvic-femoral angle (PFA), and acetabular anteinclination (AI) from lateral radiographs. The interaction of the different parameters was assessed. PROMs were compared between patients with normal spinopelvic mobility (10° ≤ ∆PT ≤ 30°) or abnormal spinopelvic mobility (stiff: ∆PT < ± 10°; hypermobile: ∆PT > ± 30°). Multiple regression and receiver operating characteristic (ROC) curve analyses were used to test for possible predictors of spinopelvic mobility. RESULTS: Standing to sitting, the hip flexed by a mean of 57° (sd 17°), the pelvis tilted backwards by a mean of 20° (sd 12°), and the lumbar spine flexed by a mean of 20° (sd 14°); strong correlations were detected. There was no difference in PROMs between patients in the different spinopelvic mobility groups. Maximum hip flexion, standing PT, and standing AI were independent predictors of spinopelvic mobility (R2 = 0.42). The combined thresholds for standing was PT ≥ 13° and hip flexion ≥ 88° in the clinical examination, and had 90% sensitivity and 63% specificity of predicting spinopelvic stiffness, while SS ≥ 42° had 84% sensitivity and 67% specificity of predicting spinopelvic hypermobility. CONCLUSION: The hip, on average, accounts for three-quarters of the standing-to-sitting movement, but there is great variation. Abnormal spinopelvic mobility cannot be screened with PROMs. However, clinical and standing radiological features can predict spinopelvic mobility with good enough accuracy, allowing them to be used as reliable screening tools. Cite this article: Bone Joint J 2019;101-B:902-909.

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.

The minipig model for experimental chondral and osteochondral defect repair in tissue engineering: retrospective analysis of 180 defects.

Articular cartilage repair is still a challenge in orthopaedic surgery. Although many treatment options have been developed in the last decade, true regeneration of hyaline articular cartilage is yet to be accomplished. In vitro experiments are useful for evaluating cell-matrix interactions under controlled parameters. When introducing new treatment options into clinical routine, adequate animal models are capable of closing the gap between in vitro experiments and the clinical use in human beings. We developed an animal model in the Göttingen minipig (GMP) to evaluate the healing of osteochondral or full-thickness cartilage defects. The defects were located in the middle third of the medial portion of the patellofemoral joint at both distal femurs. Chondral defects were 6.3 mm, osteochondral defects either 5.4 or 6.3 mm in diameter and 8 or 10 mm deep. In both defects the endogenous repair response showed incomplete repair tissue formation up to 12 months postoperatively. Based on its limited capability for endogenous repair of chondral and osteochondral defects, the GMP is a useful model for critical assessment of new treatment strategies in articular cartilage tissue engineering.

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%.

Modern Radiological Imaging of Osteoarthritis of The Hip Joint With Consideration of Predisposing Conditions.

UNLABELLED: Osteoarthritis is the most common disease of the hip joint in adults and has a high socioeconomic impact. This review article discusses the value of three imaging modalities in the diagnosis of osteoarthritis of the hip joint: projection radiography, computed tomography, and magnetic resonance imaging (MRI). Besides established imaging diagnostics of osteoarthritis, this review also outlines new MRI techniques that enable the biochemical analysis of hip joint cartilage and discusses predisposing deformities of the hip joint including femoroacetabular impingement (FAI) with labral pathologies, hip joint dysplasia, malrotation, and, finally, femoral head necrosis, for which early detection and an exact description of the extent and localization of the necrotic area are extremely important. Conventional X-rays remain indispensable for the diagnosis of osteoarthritis, while MRI is able to depict additional early symptoms and signs of activity of the disease. With the increasing number of joint-preserving interventions such as surgical hip luxation and hip joint arthroscopy for treating FAI, high-resolution imaging is gaining further importance for both pre- and postoperative diagnostics because it can accurately recognize early stages of joint damage. With high-resolution MR sequences and MR arthrography, the detailed depiction of the thin cartilaginous coating of the hip joint has become quite possible. KEY POINTS: • Projection radiography is the method of choice for the diagnostic work-up of osteoarthritis of the hip joint.• Using computed tomography, the amount of acetabular bone stock prior to total hip arthroplasty is assessed in selected patients.• Magnetic resonance imaging can substantiate the indication of surgery in case of discrepancy between clinical symptoms and radiological findings of the hip joint.• If distinct and left untreated, predisposing conditions (such as femoroacetabular impingement) may lead to early development of osteoarthritis of the hip joint.• Functional cartilage imaging can verify changes in the biochemical composition of the cartilage before they become morphologically evident. Citation Format: • Weber MA, Merle C, Rehnitz C et al. Modern Radiological Imaging of Osteoarthritis of The Hip Joint With Consideration of Predisposing Conditions. Fortschr Röntgenstr 2016; 188: 635 - 651.

[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.

[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.