Unicompartmental knee arthroplasty (UKA) in isolated medial or lateral osteoarthritis leads to good clinical results. However, revision rates are higher in comparison to total knee arthroplasty (TKA). One reason is suboptimal fitting of conventional off-the-shelf prostheses, and major overhang of the tibial component over the bone has been reported in up to 20% of cases. In this retrospective study, a total of 537 patient-specific UKAs (507 medial prostheses and 30 lateral prostheses) that had been implanted in 3 centers over a period of 10 years were analyzed for survival, with a minimal follow-up of 1 year (range 12 to 129 months). Furthermore, fitting of the UKAs was analyzed on postoperative X-rays, and tibial overhang was quantified. A total of 512 prostheses were available for follow-up (95.3%). Overall survival rate (medial and lateral) of the prostheses after 5 years was 96%. The 30 lateral UKAs showed a survival rate of 100% at 5 years. The tibial overhang of the prosthesis was smaller than 1 mm in 99% of cases. In comparison to the reported results in the literature, our data suggest that the patient-specific implant design used in this study is associated with an excellent midterm survival rate, particularly in the lateral knee compartment, and confirms excellent fitting.

Das femoroazetabuläre Impingement-Syndrom (FAIS) stellt eine präarthrotische Deformität dar. Häufig stellen sich Patienten mit FAIS erst bei bereits bestehender Koxarthrose vor. Wünschenswert wäre es, wenn durch die operative gelenkerhaltende Korrektur des FAIS die Progression der Arthrose verhindert werden könnte. Biologische Veränderungen des Gelenkmilieus, inflammatorische Prozesse und weitere gelenk- und patientenspezifische Faktoren, welche bei der operativen Korrektur nicht beeinflusst werden, scheinen auch bei der Arthroseentwicklung im Rahmen eines FAIS eine bedeutende Rolle zu spielen. Die Ergebnisse der operativen Behandlung des FAIS ab einer Arthrose Grad 2 nach Tönnis sind schlecht und häufig kann die Implantation einer Hüftendoprothese nicht vermieden werden. Auch bei Patienten mit einem FAIS und Arthrosegrad I nach Tönnis sind die Ergebnisse der gelenkerhaltenden Therapie deutlich schlechter als bei den Patienten ohne Arthrose. Da es sich meist um junge Patienten handelt, versucht man, die Implantation der Hüftendoprothese aufgrund der damit verbundenen Risiken zu verzögern. In der Therapieentscheidung hilft eine Analyse der zusätzlichen Risikofaktoren, welche für ein schlechtes Outcome der gelenkerhaltenden Therapie sprechen. Diese umfassen ein Alter über 45 Jahre, die Adipositas, einen hohen Alphawinkel, einen CE-Winkel unter 25° und das weibliche Geschlecht. Bereits bei Koxarthrose Grad 1 nach Tönnis und zusätzlichen Risikofaktoren liegt die Erfolgsrate der gelenkerhaltenden Therapie nach 5 Jahren deutlich unter 50 %, weshalb wir in diesen Fällen die konservative Therapie empfehlen. Vielversprechend scheint die Anwendung von mesenchymalen Progenitorzellen zu sein, auch wenn sie sich noch nicht in der Routine etabliert hat. Sollte die konservative Therapie nicht erfolgreich sein, ist auch bei jungen Patienten die Implantation einer Hüftendoprothese indiziert. Durch die Verwendung moderner Gleitpaarungen liegt die Überlebensrate der Hüftendoprothesen auch bei Patienten unter 50 Jahren nach 15 Jahren bei über 90 %. Die Zufriedenheit dieser Patienten ist in der Regel auch deutlich höher als nach gelenkerhaltender Hüftchirurgie. Vielversprechend für die Zukunft sind kombinierte Ansätze, welche die mechanische Korrektur des Offsets am Schenkelhals mit lokaler Applikation mesenchymaler Progenitorzellen kombinieren und somit auch von biologischer Seite die Progression der Arthrose positiv beeinflussen.

The German Arthroplasty registry (EPRD) has shown that different prosthesis systems have different rates of secondary patellar resurfacing: four years after implantation, the posterior-stabilized (PS) Vega prosthesis has a 3.2% risk of secondary patellar resurfacing compared to the cruciate-retaining (CR) Columbus prosthesis at 1.0% (both Aesculap AG, Tuttlingen, Germany). We hypothesized that PS implants have increased retropatellar pressure and a decreased retropatellar contact area compared to a CR design, which may lead to an increased likelihood of secondary patellar resurfacing. Eight fresh frozen specimens (cohort 1) were tested with an established knee rig. In addition, a possible influence of the registry-based patient collective (cohort 2) was investigated. No significant differences were found in patient data–cohort 2-(sex, age). A generally lower number of PS system cases is noteworthy. No significant increased patella pressure could be detected with the PS design, but a lower contact area was observed (cohort 1). Lower quadriceps force (100°–130° flexion), increased anterior movement of the tibia (rollback), greater external tilt of the patella, and increasing facet pressure in the Vega PS design indicate a multifactorial cause for a higher rate of secondary resurfacing which was found in the EPRD patient cohort and might be related to the PS’ principle function.

When a total knee arthroplasty (TKA) is implanted using the traditional mechanical alignment technique, this typically results in a straight leg, independently of pre-operative or even pre-arthrotic varus or valgus alignment. With mechanical alignment, we distinguish between 2 different alignment techniques: ligament balancing and bony referencing according to bony skeletal landmarks. In ligament balanced technique beside the straight mechanical axis, the prosthesis is implanted at 90 degrees to the latter. The rotational alignment of the femur is set according to the ligament tension. In the skeletal referenced technique, the rotation of the femur is also set according to bony skeletal landmarks. As a variation of this technique, the prosthesis can be implanted with anatomical alignment. In this technique, the medial slope of the joint line of 3 degrees in the frontal plane is respected during the implantation of TKA. Both techniques result in comparable long-term results with survival rates of almost 80% after 25 years. On the other hand, 15-20% of TKA patients report dissatisfaction with their clinical result. For more than 10 years now, the kinematic TKA alignment concept has been developed with the goal to achieve implantation that is adapted to the individual anatomy of the patient. The advocates of this technique expect better function of TKA. This strategy aims to reconstruct the pre-arthrotic anatomy of a given patient while preserving the existing joint line and the mechanical axis without performing ligamentary release. Studies have shown that the function of the prothesis is at least that good as in the conventional techniques. Long-term results are still sparse, but initial studies show that TKA implanted using the kinematic alignment technique exhibit comparable 10-year-survival rates to those implanted using the traditional mechanical alignment technique. Future studies need to show the limitations of this new technique and to identify patients who will or will not significantly benefit from this technique.

Abstract Background In soft tissue sarcomas (STS) radiotherapy (RTx) may be applied pre- or postoperatively with advantages and disadvantages on either side. We examined the effect of preoperative radiation on wound healing in patients with STS of the extremities and the pelvis. Methods Between August 2008 and March 2011, 32 patients with an average of 54 years (SD 18.7) and with STS (all Grade 2 or 3) were treated with a planned wide resection after neoadjuvant RTx leaving a rim of uninvolved soft tissue around the tumor. Preoperative RTx was given at an average dose of 51,5 Gy (SD 4.6) and mean follow up was 12.2 months (SD 9.8). The results were compared to a consecutive series of 60 patients treated later on without neoadjuvant RTx. Results R0 resection were performed in 31 of 32 patients. Impaired wound healing (IWH) occurred in 19 patients (59%), revision surgery had to be performed in 17 patients (53% of total). Four patients had to undergo 2 or more revisions. One patient had to be amputated and one patient died due to septic complications after revision surgery. IWH was seen more frequently in the lower (18 / 28) than in the upper extremities (1 / 4), yet this was not statistically significant in our series (p = 0.223, Fisher’s exact test). Comorbidities were not found to be of influence. In the control group, revision surgery was necessary in 18% of the patients (p = 0.0006). Conclusions Radiotherapy is effective in local tumour control, but causes a high rate of impaired wound healing (59%), if applied prior to surgery. This frequently resulted in one or more revision surgeries delaying the schedule of further therapies. The authors recommend RTx to be applied only in selected cases in a neoadjuvant setting.

Threaded cups show good clinical results when implanted correctly. In clinical use, multiple cases with an incomplete placement of the EcoFit threaded cup (implantcast) were observed. This behaviour could not be explained intra- and postoperatively. The aim of this study was to compare and optimise the drill-in-behaviour of the EcoFit cup in a biomechanical investigation. EcoFit cup sizes 46, 50 and 54 mm were compared with the SC cup (Aesculap) size 50 mm. Foam blocks (Sawbones) of density 0.16 g/ml (pcf 10), 0.32 g/ml (pcf 20) and 0.48 g/ml (pcf 30) were used. After standardised placement using a universal testing system (n = 8 per group), the primary stability, the overhang of the cups and the drill-in behaviour were measured. Overreamings of 1 and 2 mm were performed (pcf 20, n = 8) for the EcoFit cup size 50 and the primary stability as well as the overhang measurements were examined. Measurements of the cup diameter, thread depth and thread pitch were performed on three-dimensional (3D) images of the cup size 50 mm. The drill-in behaviour was different between the EcoFit and the SC cups. Even with maximum torque, the EcoFit cup could not be positioned as deep as the SC cup in standard reaming conditions (overhang of 1.1 ± 0.4 mm for the EcoFit size 50 in pcf 20 and of -0.01 ± 0.2 mm for the SC cup). The primary stability was lower for the EcoFit cup in comparison to the SC cup (128.8 ± 3.2 Nm vs. 138.6 ± 9.1 Nm, p = 0.0291). With overreaming to 51 mm, a deeper positioning of the EcoFit was possible (overlap of -0.3 ± 0.1, comparable to the SC cup). The overreaming of the cavity also led to a significantly higher primary stability of 143.4 ± 3.7 Nm (p < 0.001) comparable to the unaltered condition (128.8 ± 3.2 Nm). Overreaming to 52 mm had no further advantage in terms of primary stability or overhang. The geometric measurements showed significant differences as well. The previously clinically observed difficulties in inserting the cup were confirmed by this study. By overreaming to 51 mm, the drill-in behaviour, the primary stability and the measured overhang were comparable to the reference cup. The obtained results suggest that the extension of the acetabulum cavity to 51 mm while using the implantcast EcoFit size 50 should be implemented in clinical applications.

Metal wear debris and released ions (CoCrMo), which are widely generated in metal-on-metal bearings of hip implants, are also found in patients with metal-on-polyethylene bearings due to the mechanically assisted crevice corrosion of modular taper junctions, including head-neck and neck-stem taper interfaces. The resulting adverse reactions to metal debris and metal ions frequently lead to early arthroplasty revision surgery. National guidelines have since been published where the blood metal ion concentration of patients must consistently be monitored after joint replacement to prevent serious complications from developing after surgery. However, to date, the effect of metal particles and metal ions on local biological reactions is complex and still not understood in detail; the present study sought to elucidate the complex mechanism of metal wear-associated inflammation reactions. The knee joints in 4 groups each consisting of 10 female BALB/c mice received injections with cobalt chrome ions, cobalt chrome particles, and ultra-high-molecular-weight polyethylene (UHMWPE) particles or PBS (control). Seven days after injection, the synovial microcirculation and knee joint diameter were assessed via intravital fluorescence microscopy followed by histological evaluation of the synovial layer. Enlarged knee diameter, enhanced leukocyte to endothelial cell interactions, and an increase in functional capillary density within cobalt chrome particle-treated animals were significantly greater than those in the other treatment groups. Subsequently, pseudotumor-like tissue formations were observed only in the synovial tissue layer of the cobalt chrome particle-treated animals. Therefore, these findings strongly suggest that the cobalt chrome particles and not metal ions are the cause for in vivo postsurgery implantation inflammation.

Purpose: Malposition of implant components in total knee arthroplasty (TKA) has consequences on tibiofemoral kinematics, contact forces and ligament tensions. To evaluate the impact of tibial baseplate malpositioning in the same knee, we conducted a computer simulation. Methods: An established weight-bearing finite element model of a fixed bearing TKA was used for the computer simulation. To evaluate the influence of tibial baseplate malposition, calculations were consecutively performed in neutral position, at 3 degrees and 6 degrees of internal and external rotation and at 3 mm and 6 mm of medial and lateral translation. Results: The highest effect of malposition was observed for ligament tensions, with a tendency of a greater influence for the 6 mm translation compared to 6 degrees of rotation. Changes in contact forces and tibiofemoral kinematics were according to the alterations of ligament tensions. The highest ligament tension, contact force and femoral roll-back were registered for 6 mm medialization of the tibial baseplate. Discussion: Tibial baseplate malposition effects ligament tensions, tibiofemoral contact forces and kinematics and has a risk of unfavorable clinical results due to postoperative pain, reduced range of motion, instability and a higher rate of early loosening. Therefore, surgeons should aim for a neutral position of the tibial baseplate.

ObjectivesAcetabular bone defect quantification and classification is still challenging. The objectives of this study were to suggest and define parameters for the quantification of acetabular bone defects, to analyze 50 bone defects and to present the results and correlations between the defined parameters.MethodsThe analysis was based on CT-data of pelvises with acetabular bone defects and their reconstruction via a statistical shape model. Based on this data, bone volume loss and new bone formation were analyzed in four sectors (cranial roof, anterior column, posterior column, and medial wall). In addition, ovality of the acetabulum, lateral center-edge angle, implant migration, and presence of wall defects were analyzed and correlations between the different parameters were assessed.ResultsBone volume loss was found in all sectors and was multidirectional in most cases. Highest relative bone volume loss was found in the medial wall with median and [25, 75]-percentile values of 72.8 [50.6, 95.0] %. Ovality, given as the length to width ratio of the acetabulum, was 1.3 [1.1, 1.4] with a maximum of 2.0, which indicated an oval shape of the defect acetabulum. Lateral center-edge angle was 30.4° [21.5°, 40.4°], which indicated a wide range of roof coverage in the defect acetabulum. Total implant migration was 25.3 [14.8, 32.7] mm, whereby cranial was the most common direction. 49/50 cases showed a wall defect in at least one sector. It was observed that implant migration in cranial direction was associated with relative bone volume loss in cranial roof (R = 0.74) and ovality (R = 0.67).ConclusionWithin this study, 50 pelvises with acetabular bone defects were successfully analyzed using six parameters. This could provide the basis for a novel classification concept which would represent a quantitative, objective, unambiguous, and reproducible classification approach for acetabular bone defects.

Die dysplastische Hüftpfanne wird in dreidimensionaler Weise nach lateral und ventral geschwenkt.

Introduction Sexuality is an important factor in quality of life (QoL) and was reported to improve after total joint arthroplasty (TJA). However, one study group found evidence regarding a high rate of impaired erectile function of about 20% in male patients after TJA. As erectile dysfunction is a serious matter of concern and there are no data explaining this observation sufficiently, the purpose of this study was to revaluate the erectile function in patients after TJA. Material and methods All consecutive male patients scheduled for TJA were enrolled in this prospective study. Evaluation was performed pre- and 6 months postoperatively with the International Index of Erectile Function (IIEF-5) questionnaire. One hundred and fifty-nine patients fulfilled the inclusion criteria, and 51 patients wished not to take part in the study. Results From the 108 patients who were included prior to surgery, 101 (94%) were available at the 6-month follow-up. In those patients, the preoperative erectile function was normal in 38 (24.0 ±1.1), impaired in 45 (14.7 ±6.5) and with no function in 18 patients. No significant difference in the pre- (15.4 ±9.3) and postoperative (15.3±9.2) IIEF-5 score was observed (p = 0.59) in the total group. Similarly, subgroup analysis revealed no significant difference in patients with total hip arthroplasty (p = 0.58), total knee arthroplasty (p = 0.37) or > 70 years (p = 0.08). Conclusions The previously reported high rate of impaired erectile function after TJA of the lower extremity could not be confirmed. Total joint arthroplasty remains a safe procedure in terms of postoperative erectile function.

Introduction Unicompartmental arthroplasty (UKA) of the knee in patients with isolated medial osteoarthritis yields adequate results; however, the survival rate is inferior to that of total knee arthroplasty (TKA). A key factor in the longevity of the implant is the positioning; however, the optimal tibial slope in UKA has not been determined. The aim of this study was to establish a finite element (FE) model and investigate the effect of the tibial slope on the strain of the ligaments, kinematics, inlay movement, and load in the nonreplaced patellofemoral compartment in a medial mobile bearing UKA. Materials and Methods An FE model of a leg was established with a virtual UKA implantation with three different tibial slopes (0°, 5°, and 10°). Subsequently, the knee was flexed from 14–73°. In addition, the ground reaction force and the muscles were simulated. Results With a higher tibial slope, there was more external rotation of the tibia. An increased tibial slope provided a lateral shift of the patella in the trochlear groove and a more anterior position of the inlay. The ligament strains were also changed, specifically, the anterior portion of the medial collateral ligament and the posterior cruciate ligament (PCL). Discussion This study established the first model of a quasidynamic mobile bearing UKA in a leg under weight-bearing conditions. With an increasing tibial slope, there was a higher external rotation of the tibia that created different femorotibial and retropatellar kinematics and different strains in the ligaments. This knowledge adds important information for the optimal tibial slope that has to be determined individually depending on the patient's preoperative kinematics, desired postoperative kinematics, ligament status, and location of the retropatellar chondral damage.

Background: Surgical treatment of late diagnosed development dysplasia of the hip (DDH) remains challenging with several methods being described. We therefore retrospectively evaluated the outcome of Salter innominate osteotomy (SIO) in patients with fully-grown bone, to evaluate whether this surgical procedure allows sufficient acetabular correction. Material and methods: Between 2004-2012 SIO had been performed in 45 patients (49 hips) with late diagnosed DDH. The evaluation included pre- and postoperative radiographs (n= 49), the complication rate (n= 49) and the clinical outcome (WOMAC, HHS, UCLA) (n= 34). Results: Mean age at surgery was 27.6 (16-51) with a follow-up of 6.7 +/- 2.7 (0.9-11.0) years. Radio-logically, a good acetabular correction with a significant improvement of the Center Edge angle (15.4 degrees to 34.90), sharps angle (45.7 degrees to 32.0 degrees) and migration percentage (33.2% to 14.4%) (p < 0.001) was found. Clinical results revealed a WOMAC of 13.9 +/- 13.3, UCLA of 7.8 +/- 2.1 and HHS of 85.0 +/- 11.8. Complications were noted for 10 patients (20%) with 7 (14%) requiring revision. Conclusion: The results demonstrated that SIO achieved a satisfying acetabular correction and good clinical results in late diagnosed DDH. It therefore might be an option in some cases, although periacetabular osteotomy techniques are currently preferable used as they allow a wider range of acetabular correction. (C) 2018 Published by Elsevier Masson SAS.

Surgical treatment of late diagnosed development dysplasia of the hip (DDH) remains challenging with several methods being described. We therefore retrospectively evaluated the outcome of Salter innominate osteotomy (SIO) in patients with fully grown bone, to evaluate whether this surgical procedure allows sufficient acetabular correction. Between 2004–2012, SIO had been performed in 45 patients (49 hips) with late diagnosed DDH. The evaluation included pre- and postoperative radiographs (n = 49), the complication rate (n = 49) and the clinical outcome (WOMAC, HHS, UCLA) (n = 34). Mean age at surgery was 27.6 (16–51) with a follow-up of 6.7 ± 2.7 (0.9–11.0) years. Radiologically, a good acetabular correction with a significant improvement of the Center Edge angle (15.4 to 34.9), Sharps angle (45.7 to 32.0) and migration percentage (33.2% to 14.4%) (p < 0.001) was found. Clinical results revealed a WOMAC of 13.9 ± 13.3, UCLA of 7.8 ± 2.1 and HHS of 85.0 ± 11.8. Complications were noted for 10 patients (20%) with 7 (14%) requiring revision. The results demonstrated that SIO achieved a satisfying acetabular correction and good clinical results in late diagnosed DDH. It therefore might be an option in some cases, although periacetabular osteotomy techniques are currently preferable used as they allow a wider range of acetabular correction. IV, retrospective observational study.

PURPOSE:Short-stem hip arthroplasty (SHA) was designed to preserve bone stock and provide an improved load transfer. To gain more evidence regarding the load transfer, this review analysed the periprosthetic bone remodelling of SHA in comparison to standard hip arthroplasty (THA).METHODS:PubMed and ScienceDirect were screened to extract dual-energy X-ray absorptiometry (DXA) studies evaluating the periprosthetic bone remodelling of SHA and two proven THA designs. From the studies included, the postoperative change in periprosthetic bone mineral density (BMD) after one year and the trend over two years was determined.RESULTS:Fifteen studies with four SHAs (CFP, Metha, Nanos, Fitmore) and two THAs (CLS and Bicontact) designs were included. All SHA and THA stems revealed an initial decrease at the calcar and major trochanter (Gruen 1 and 7) with the Metha, Nanos and Fitmore showing a smaller and more balanced remodelling compared to THA. The pattern after one year and the trend over two years argue for a methaphyseal anchorage of the Metha and Nanos, whereas the Fitmore and CFP seem to anchor metha-diaphyseal. Clearly different pattern of bone remodelling were observed between all four SHAs.CONCLUSIONS:Periprosthetic bone remodelling is also present in SHA, with the main bone reduction observed proximally. However, certain SHA stems show a more balanced remodelling compared to THA, arguing for a favourable load transfer. Also, the femoral length where bone remodelling occurs is clearly shorter in SHA. As distinctively different pattern between the SHA designs were observed, they should not be judged as a single implant group.

Total knee arthroplasty (TKA) leaves 11–25% of the patients unsatisfied, and patellofemoral joint pain is one cause. This study aimed to compare the differences between kinematics and load transfer in the same knee with axial internal/external rotation of the femoral component (CoRo) versus a separate axial internal/external trochlear groove rotation (TrRo) which is included in the TKA trochlea design.

Beim Wechsel einer Hüfttotalendoprothese (Hüft-TEP) ist häufig eine der in situ liegenden Komponenten (Pfanne/Schaft) noch fest verankert und muss nicht gewechselt werden. Die implantierte Komponente muss mit dem in situ verbleibenden Implantat kompatibel sein. Die Vermischung der Implantate unterschiedlicher Firmen kann zu einem sog. Mismatch (nicht kompatibel) oder einem Mix & Match (kompatibel) führen.

Short stem total hip arthroplasty (SHA) has gained increasing popularity as it conserves bone stock and is supposed to allow revision with a conventional stem. However, no study has evaluated whether the revision of a SHA with a standard total hip arthroplasty (THA) stem provides sufficient primary stability to allow osseous integration.

In case of hip revision arthroplasty, one component (cup/stem) is often well fixed and does not need to be exchanged. The newly implanted component needs to be compatible with the well-fixed implant. The combination of implants from different companies leads to "mix and match" or even mismatch between the implants.The objective of this work was to describe possible combinations including their specifications that need to be considered in partial exchange of hip prostheses. For this purpose the literature, surgical techniques of companies and judgements concerning this topic were analysed and our own results and experiences were included.Partial revision arthroplasty can be challenging and needs to be planned in detail. In case of isolated cup or inlay revision with exchange of a modular head the cone of the stem needs to be identified. A ceramic head may be used in revision with a titanium sleeve even from a different company as long as they are compatible. Patients however need to give their informed consent for this mix and match procedure. This procedure is done frequently and good study results support this, however from a juristic point of view a definite recommendation cannot be given. If the inlay of a cup is replaced, the original inlay should be used. If this is not available anymore, it can be manufactured as a special product in many cases. If this is also not possible, an inlay can also be cemented into a well-fixed cup. Biomechanical and clinical studies support this off-label technique. In case of an isolated exchange of the stem with a ceramic inlay that is retained in a well-fixed cup, the revision stem and ceramic head need to be from the same company as the cup. In case of ceramic fracture, a ceramic head with a titanium sleeve should be combined with a PE or ceramic inlay, a metal head or inlay should never be used.