Status and future of modern technologies in arthroplasty : Results of a survey of the German Society for Orthopedics and Trauma Surgery (DGOU).

BACKGROUND: The orthopedic community is divided on the question of whether modern technologies in arthroplasty improve outcomes. Therefore, the aim of this initiative of the working group on intraoperative imaging and technology integration (Arbeitsgemeinschaft intraoperative Bildgebung und Technologieintegration, AGiTEC) is to initiate the collection of additional data for the scientific evaluation of modern technologies. QUESTION: To what extent are modern technologies currently used and which implementations are planned? Do the members of the German Society for Orthopedics and Trauma Surgery (DGOU) consider the acquisition of additional data for scientific assessment necessary? METHODS: Members of the DGOU were asked via an e­mail survey about the distribution and projected introduction of modern technologies in arthroplasty. They were also asked whether sufficient data were collected for scientific evaluation and whether acquisition of additional data in studies or arthroplasty registries were considered necessary. RESULTS: Of the 7923 probands surveyed, 428 completed the questionnaire in full (5.4%). It was found that individual implants and navigation are currently the most frequently used (31% and 29%, respectively). The largest increases in the next 2 years are projected for virtual reality and robotics (+30% and +23%, respectively), 85% of respondents indicated that insufficient data were collected for scientific evaluation, and 89% each requested initiation of multicenter studies and inclusion of technologies in the arthroplasty registry. CONCLUSION: The results of this study should motivate the scientific community, industry, and those responsible for the arthroplasty registries to collect and analyze data for the scientific assessment of modern technologies.

Current evidence base for kinematic alignment.

BACKGROUND: Kinematic alignment recently became an alternative alignment option for total knee arthroplasty (TKA). Beside previous studies assessing mechanical alignment in comparison to unintentional malalignment of TKA in terms of implant survival and clinical outcome, more and more studies have focused on the direct comparison of intentional kinematic alignment with mechanical alignment of the prosthesis. In the past 5 years the number of studies with respect to kinematic alignment has risen from 11 to 91 studies. AIM: The aim of this review article is to give a narrative overview of the current literature in the debate concerning kinematic and mechanical alignment in TKA.

[PSI-technique for kinematic alignment]. / PSI ­ Technik des kinematischen Alignments.

BACKGROUND: Compared with the current gold standard of knee endoprosthetics, the concept of kinematic alignment is more responsive to the individual anatomy of the patient as it enables the three-dimensional restoration of individual axes, joint lines and capsule tension. One point of criticism is the lack of intraoperative control over individual bone resections with conventional instrumentation. However, with the help of CT-based individual 3D-printed cutting blocks, a precise preoperative plan can be transferred to the operating room. The aim of this article is to explain the operative technique of patient-specific instrumentation (PSI)-protected kinematic alignment. METHODS: The procedure is based on a preoperative 3D model of the bony anatomy of the patient, with the aid of which the planning of the operation, with the positioning and size of the implant, as well as the necessary bone resections, are carried out. With this information about anatomy and resection levels the individual cutting blocks are produced, aided by a 3D printer. Intraoperative control is achieved by measuring the resection by means of a gage and comparison with the digital 3D design. DISCUSSION: With the aid of the 3D-printed PSI cutting blocks the preoperative plan of kinematic alignment can be implemented in a precise manner. It is a simple tool and does not require any great expense. Compared with the conventional instrumentation, the operating time is shortened. However, because of the purely CT-based design, no information about the state of the soft tissue is obtained.

Clinical validation and accuracy testing of a radiographic decision aid for unicondylar knee arthroplasty patient selection in midterm follow-up.

PURPOSE: The purpose of this study was to examine the predictive value concerning clinical outcome and implant survival, as well as the accuracy of individual tests of a recently published radiographic decision aid for unicondylar knee arthroplasty indication findings. METHODS: In the retrospective part of the study, 98 consecutive patients who had undergone unicondylar knee arthroplasty (Phase 3 Oxford medial UKA) were included, using revision questionnaires, as well as the Forgotten Joint Score-12 (FJS-12) and Knee Osteoarthritis Outcome Score (KOOS) and analysed for suitability of the radiographic decision aid. Inappropriate and appropriate indications were then compared concerning the clinical outcome and implant survival. The prospective part of the study assessed the accuracy of the decision aid's radiographic tests (varus and valgus stress views, true lateral view and skyline view), and included 90 patients. Definition as appropriate for UKA procedure included medial bone-on-bone situation in varus stress views, full-thickness lateral cartilage and functional medial collateral ligament in valgus stress views, functional anterior cruciate ligament (ACL) in true lateral views and absence of lateral facet osteoarthritis with bone loss in skyline views. Pre-operative radiographic assessment with respect to the decision aid was then compared with intraoperative articular conditions. The clinical outcome was analysed using non-parametric tests (Mann-Whitney U), and revision rates were compared using the Fisher's exact test. Accuracy assessment included calculations of the sensitivity, specificity, negative predictive value and positive predictive value. A p value < 0.05 was considered statistically significant. RESULTS: Appropriate unicondylar knee arthroplasty with respect to the decision aid showed a significantly lower revision rate compared to inappropriate unicondylar knee arthroplasty (7.3% vs. 50.0%, p < 0.0001), as well as higher clinical outcome scores (FJS-12: 53.13 vs. 31.25, p = 0.041 and KOOS-QDL: 68.75 vs. 50.0, p = 0.036). The overall sensitivity (70.1%) and specificity (76.2%) for the radiographic decision aid was comparably low, which was essentially based on false negative cases (22.7%) regarding medial bone-to-bone conditions. CONCLUSION: The radiographic decision aid is a helpful tool to predict clinical outcome and implant survival of mobile-bearing unicondylar knee arthroplasty. Strict use of the radiographic decision aid may lead to increased exclusion of appropriate patients with unicondylar knee arthroplasty implantation.

Three-dimensional templating in hip arthroplasty: the basis for template-directed instrumentation?

INTRODUCTION: Computed tomography-based three-dimensional models may allow the accurate determination of the center of rotation, lateral and anterior femoral offsets, and the required implant size in total hip arthroplasty. In this cadaver study, the accuracy of anatomical reconstruction was evaluated using a three-dimensional planning tool. MATERIALS AND METHODS: A total of eight hip arthroplasties were performed on four bilateral specimens. Based on a computed tomography scan, the position and size of the prosthesis were templated with respect to the anatomical conditions. RESULTS: On average, all parameters were reconstructed to an accuracy of 4.5 mm and lie within the limits recommended in the literature. All prostheses were implanted with the templated size. CONCLUSIONS: The exact anatomy of the patient and the required size and position of the prosthesis were precisely analyzed using a templating software. Based on the present findings, the development of template-directed instrumentation is conceivable using this method. However, further technical features (e.g., navigation or robot-assisted surgery) are required for improved precision for implant positioning.

Biomechanical properties of adjustable extracortical graft fixations in ACL reconstruction.

BACKGROUND: Reliable biomechanical data about the strength of different tibial extracortical graft fixation devices is sparse. This biomechanical study compares the properties of tibial graft fixation in ACL reconstruction with either the ACL Tight Rope™ or the Rigid Loop Adjustable™ device. The hypothesis was that both fixation devices would provide comparable results concerning gap formation during cyclic loading and ultimate failure load. METHODS: Sixteen sawbone tibiae (Sawbones™) underwent extracortical fixation of porcine flexor digitorum profundus grafts for ACL reconstruction. Either the ACL Tight Rope™ (Arthrex) or the Rigid Loop Adjustable™ (DePuy Mitek) fixation device were used, resulting in 2 groups with 8 specimens per group. Biomechanical analysis included pretensioning the constructs 10 times with 0.75 Hz, then cyclic loading of 1,000 position-controlled cycles and 1,000 force-controlled cycles applied with a servohydraulic testing machine. Elongation during cyclic loading was recorded. After this, ultimate failure load and failure mode analysis were performed. RESULTS: No statistically significant difference could be noted between the groups regarding gap formation during cyclic loading (4.6 ± 2.6 mm for the Rigid Loop Adjustable™ vs. 6.6 ± 1.5 mm for the ACL Tight Rope™ (p > 0.05)), and ultimate failure loads (980 ± 101.9 N for the Rigid Loop Adjustable™ vs. 861 ± 115 N ACL Tight Rope™ (p > 0.05)). CONCLUSION: ACL Tight Rope™ and the Rigid Loop Adjustable™ fixation devices yield comparable biomechanical results for tibial extracortical graft fixation in ACL reconstruction. These findings may be of relevance for the future surgical decision-making in ACL reconstruction. Randomized controlled clinical trials comparing both fixation devices are desirable for the future.

[Robotics-mechanical bridge between imaging and patient]. / Robotik ­ maschinelle Brücke zwischen Bildgebung und Patient.

BACKGROUND: There are still a high number of dissatisfied knee arthroplasty patients. This situation has not changed much for decades, despite many innovations focusing on implant longevity and higher procedural precision. In this context, there is a growing discussion on possible systematic errors made in knee arthroplasty, especially regarding the alignment philosophy of the implants. OBJECTIVE: It was reported that a more anatomical alignment might result in improved patient outcome. However, current technologies have severe limitations to achieving optimized and individual alignment. In this context, the aim of this manuscript was to assess whether image-based robot-guided knee arthroplasty might represent an opportunity for achieving individualized alignment. METHODS: The literature on this subject was evaluated and analyzed. Furthermore, research projects and expert recommendations were discussed. RESULTS: The precision of preoperative planning is higher with robotic techniques than with other computer-assisted or manual technologies. In addition, the individual soft tissue situation of the patient is taken into account and the prosthesis position is optimized. This ensures optimum soft tissue balancing and stability of the prosthesis. CONCLUSION: Modern robot-assisted systems are the mechanical bridge between imaging and patient. This technique provides objective control over the results produced with alternative alignments. This applies to both the prosthesis position itself and the resulting soft tissue balancing.

Outcome of kinematic alignment using patient-specific instrumentation versus mechanical alignment in TKA: a meta-analysis and subgroup analysis of randomised trials.

INTRODUCTION: Kinematic alignment (KA) in total knee arthroplasty (TKA) matches component position to the pre-arthritic anatomy of an individual patient, with the aim of improving functional outcomes. Recent randomised controlled trials (RCTs) comparing KA to traditional neutral mechanical alignment (MA) have been mixed. This collaborative study combined raw data from RCTs, aiming to compare functional outcomes between KA using patient-specific instrumentation (PSI) and MA, and whether any patient subgroups may benefit more from KA technique. MATERIALS AND METHODS: A literature search in PubMed, EMBASE and Cochrane databases identified four randomised controlled trials comparing patients undergoing TKA using PSI-KA and MA. Unpublished data including Western Ontario McMaster Universities Arthritis Index (WOMAC) and Knee Society Score (KSS) were obtained from study authors. Meta-analysis compared MA to KA change (post-op minus pre-op) scores. Subgroup-analysis on KA patients looked for subgroups more likely to benefit from KA and the impact of PSI accuracy. RESULTS: Meta-analyses of change scores in 229 KA patients versus 229 MA patients were no different from WOMAC (mean difference 3.4; 95% confidence interval - 0.5 to 7.3), KSS function (1.3, - 3.9 to 6.4) or KSS combined (7.2, - 0.8 to 15.2). A small advantage was seen for KSS pain in the KA group (3.6, 95% CI 0.2-7.1). Subgroup-analysis showed no difference between varus, valgus and neutral pre-operative alignment groups, and those who did and did not achieve KA plans. Pain-free patients at 1-year were more likely to achieve KA plans. CONCLUSION: Patient-reported outcome scores following TKA using PSI-KA are similar to MA. No identifiable subgroups benefited more from KA, and long-term results remain unknown. Inaccuracy of the PSI system used in KA patients could potentially affect outcome.

In vivo heterotopic culturing of prefabricated tendon grafts with mechanical stimulation in a sheep model.

BACKGROUND: The goal of this study is to investigate the biomechanical and histological properties of in vivo heterotopically prefabricated cruciate ligament replacement grafts with and without mechanical stimulation. The clinical goal is to heterotopically prefabricate a bone-tendon-bone graft for anterior cruciate ligament reconstruction, which allows rapid ingrowth and early full weight bearing. METHODS: In a sheep model, eight quadriceps tendon grafts were harvested and introduced into culture chambers at their proximal and distal ends. In group S, four tendon-chamber constructs were mechanically stimulated by direct attachment to the quadriceps tendon and patella. In group NS, the same constructs were cultured without proximal attachment. All sheep were sacrificed six weeks postoperatively and the constructs were examined biomechanically and histologically. The healthy contralateral ACL and quadriceps tendon were used as controls. RESULTS: Macroscopically, no obvious ossification could be observed at the ends of the tendon-chamber constructs six weeks postoperatively. Histologically, the tendon tissue from the mechanically stimulated constructs revealed higher counts of cells and capillaries. However, there was less regular cell distribution and collagen fiber orientation compared to the control group. In addition, osteoblasts and osteogenesis were observed in the prefabricated constructs both with and without mechanical stimulation. Biomechanically, there were no significant differences in stiffness, elongation and ultimate failure load between the groups. CONCLUSION: In vivo heterotopic culture of prefabricated tendon grafts may have the potential to stimulate osteoblasts and induce osteogenesis. Future studies with longer follow-up and modifications of the surgical technique and culture conditions are desirable.

Skin signs of primary immunodeficiencies: how to find the genes to check.

Primary immunodeficiencies (PIDs) are a heterogeneous group of rare diseases that result from defects in immune system development and/or function. The clinical manifestations of PIDs are highly variable, but most disorders involve at least an increased susceptibility to infection. Furthermore, cutaneous manifestations are very common in PIDs. As an easily accessible organ, the skin can be crucial for early diagnosis and treatment. This is relevant for preventing significant disease-associated morbidity and mortality. We provide a table that enables the reader to find the possible diseases and corresponding gene defects based on the skin manifestations of the suspected PIDs. To our knowledge, this is the first review that allows the reader to find relevant PIDs and the respective gene defects through solitary or combined skin signs.

[Light protection for xeroderma pigmentosum]. / Lichtschutz bei Xeroderma pigmentosum.

Xeroderma pigmentosum is a rare autosomal recessive disorder which is caused by germinal mutations responsible for the repair of ultraviolet (UV) radiation-induced DNA lesions. It is characterized by hypersensitivity to UV radiation, poikiloderma, ocular surface disease, and in some patients pronounced sunburn and neurological disease. Patients have a very high risk of developing ocular and skin cancer on exposed body sites. No cure is available for these patients except complete protection from all types of UV radiation.

Femoral interference screw fixation of hamstring and quadriceps tendons for ACL reconstruction.

PURPOSE: This cadaveric study compares the biomechanical properties of femoral graft fixation in ACL reconstruction of either quadriceps or hamstring tendon grafts with four different interference screws. The hypothesis was that quadriceps tendon grafts provide at least equal results concerning gap formation during cyclic loading and ultimate failure load compared to hamstring tendon grafts with four different interference screws. METHODS: Eighty porcine femora underwent interference screw fixation of human tendon grafts for ACL reconstruction. Either quadriceps (Q) or hamstring (H) tendon grafts and four different bioabsorbable interference (Wolf (W), Storz (S), Mitek (M), Arthrex (A)) screws were used, resulting in 8 groups with 10 specimens per groups (WQ, WH, SQ, SH, MQ, MH, AQ, AH). Biomechanical analysis included pretensioning the constructs with 60 N for 30 s, then cyclic loading of 500 cycles between 60 and 250 N at 1 Hz in a servohydraulic testing machine, with measurement of elongation and stiffness including video measurements. After this, ultimate failure load and failure mode analysis were performed. RESULTS: No statistically significant difference could be noted between the groups regarding gap formation during cyclic loading [Cycles 21-500 (mm): WQ 3.6 ± 0.8, WH 3.9 ± 1.4, SQ 3.6 ± 0.8, SH 3.3 ± 1.5, MQ 4.3 ± 0.8, MH 4.6 ± 1.0, AQ 4.8 ± 0.8, AH 4.3 ± 1.5, n.s.], stiffness during cyclic loading [Cycles 21-500 (N/mm): WQ 72.9 ± 16.9, WH 71.6 ± 20.7, SQ 69.5 ± 23.9, SH 77.4 ± 25.1, MQ 59.6 ± 11.2, MH 48.4 ± 15.4, AQ 48.8 ± 12.7, AH 51.9 ± 22.2, n.s.], and ultimate failure load [(N): WQ 474.4 ± 88.0, WH 579.3 ± 124.2, SQ 493.9 ± 105.2, SH 576.0 ± 90.4, MQ 478.6 ± 59.0, MH 543.9 ± 119.7, AQ 480.2 ± 93.8, AH 497.8 ± 74.2, n.s.]. CONCLUSIONS: Quadriceps tendon grafts yield comparable biomechanical results for femoral interference screw fixation in ACL reconstruction compared to hamstring tendon grafts. From a clinical perspective, quadriceps tendon grafts should therefore be considered as a good option in ACL reconstruction in the future.

Non-Operative Management of Rotator Cuff Tears.

BACKGROUND: The role of nonoperative management for rotator cuff tears remains a matter of debate. Clinical results reported in the literature mainly consist of level IV studies, oftentimes combining a mixed bag of tear sizes and configurations, and are contradictory to some extent. METHODS: A selective literature search was performed and personal surgical experiences are reported. RESULTS: Most studies show an overall success rate of around 75% for nonoperative treatment. However, the majority of studies also present a progression of tear size and fatty muscle infiltration over time, with however debatable clinical relevance for the patient. Suggested factors associated with progression of a rotator cuff tear are an age of 60 years or older, full-thickness tears, and fatty infiltration of the rotator cuff muscles at the time of initial diagnosis. CONCLUSION: Non-operative management is indicated for patients with lower functional demands and moderate symptoms, and/or of course for those refusing to have surgery. Close routinely monitoring regarding development of tear size should be performed, especially in patients that remain symptomatic during nonoperative treatment. To ensure judicious patient counseling, it has to be taken into account that 1) tears that are initially graded as reparable may become irreparable over time, and 2) results after secondary surgical therapy after failed nonoperative treatment are usually reported to be inferior to those who underwent primary tendon repair.

Arthroplasty-center related retrospective analysis of risk factors for Periprosthetic Joint Infection after primary and after revision Total Hip Arthroplasty.

BACKGROUND: Periprosthetic Joint Infection (PJI) poses a great challenge to patients, surgeons and health care systems. Comorbid diseases and patient-related risk factors are poorly understood. OBJECTIVE: The purpose of this study was to evaluate patient-related risk factors for PJI after primary and after revision Total Hip Arthroplasty (THA). METHODS: In the present study, data was collected from 566 patients who underwent primary or revision THA between July 2011 and June 2012 in an established arthroplasty center (Endocert certified endoprosthesis center, EPZmax). The effects of demographic data and comorbid diseases on revision operations within 18 months following THA were analyzed using descriptive and explorative statistics. RESULTS: It was shown, that alcohol abuse, depression, preoperative ESBL (Extended Spectrum ß-Lactamase bacteria) infection, elevated preoperative serum-CRP (C-reactive protein), extended operation-time, extended length of hospital-stay, intraoperative complications, perioperative urinary tract infections and postoperative antibiotic therapy are significantly related to PJI in primary THA. CONCLUSIONS: Comorbid diseases seem to influence outcome after THA. They are important for predicting revision operations and implant survival. In severe high-risk cases, they can lead to perform the operation under precaution or to avoid performing the operation entirely. This should reduce PJI occurrences in future.

[Custom-fit kinematic alignment in total knee arthroplasty using PSI. The story of ShapeMatch technology]. / Patientenindividuelle kinematische Prothesenausrichtung per Schnittblocktechnik. Die Chronik der ShapeMatch-Technologie.

BACKGROUND: The story of ShapeMatch® custom-fit cutting guides for primary total knee arthroplasty (TKA) is special compared to other available techniques. First, it was the first such patient-specific instrument (PSI) on the market. Second, the underlying philosophy of kinematic alignment is unique compared to other competitors. Finally, it is the only PSI technique that has been withdrawn from the market. OBJECTIVES AND METHODS: The objective of this paper is to summarize the history of the ShapeMatch® technology and to review the current literature regarding clinical evidence for kinematically aligned TKA. RESULTS AND CONCLUSIONS: In the recent literature, faster rehabilitation, better knee function and higher patient satisfaction are described for kinematically aligned TKA compared to conventional alignment. However, there is also evidence for inaccuracies by using the PSI technology as a possible cause of treatment failures. Due to those problems, this technology was recalled from the market. As an alternative method to achieve kinematic alignment in TKA, manual as well as computer-assisted techniques are currently under development and are discussed here.

[Kinematic alignment in total knee arthroplasty : Concept, evidence base and limitations]. / Kinematisches Alignment in der Knieendoprothetik : Konzept, Evidence und Limitation.

BACKGROUND: Against the background that 20 % of patients are dissatisfied after total knee arthroplasty, there is ongoing controversy about optimal alignment. In this context, orientating the prosthetic components to the natural kinematic axes of the knee appears to be an interesting new concept. METHODS: The objective of this paper is to provide a critical review of the current literature and our own research data regarding the concept of kinematically aligned total knee arthroplasty with the current evidence base and potential limitations. RESULTS AND DISCUSSION: In the recent literature faster rehabilitation, better knee function, and higher patient satisfaction are described compared to conventional alignment, even if the postoperative alignment deviates more than 3° from the mechanical axis. However, the technique may not be suitable for every patient and pathology, and further research is necessary to set the correct indication.

[Patella in Place Balancer: Technique for total knee arthroplasty]. / Patella-in-Place-Balancing : Technik für die Knieprothetik.

BACKGROUND: The gap-balancing technique is well established in primary total knee arthroplasty to determine femoral rotation and flexion gap stability. However, it has been reported that the everted or luxated extensor mechanism during this procedure in addition to soft tissue releases performed may cause inaccurate flexion-gap determination and thus result in malpositioning of the femur or instability. In this article the alternative technique of a Patella in Place Balancer (PIPB) with a no tissue release philosophy is introduced. METHOD: In this procedure, at first, the tibia resection is performed and a tibia baseplate inserted. Then, two pins are drilled into the sagittal profile of the femoral condyles. After anatomical repositioning of the extensor apparatus the pins are screwed in until the flexion gap is spanned. In this position femoral component orientation is determined parallel to the tibia. We describe the current clinical experience based on a retrospective review of 3,000 patients. Moreover, initial results of a prospective study are outlined. RESULTS: The PIPB technique was suitable for the treatment of primary and secondary gonarthrosis if the collateral ligaments were intact. The detected revision rate was about 1.21 %. Only 2 % of the treated patients reported back with an unsatisfactory outcome 1 year after surgery. In the prospective survey of 33 patients a significant improvement in the KOOS Score could be documented (29.3 points preoperatively vs. 63.5 postoperatively (p < 0.05)). DISCUSSION: The PIPB overcomes the major limitation of the gap balancing technique with regard to the inaccuracy caused by the dislocated extensor mechanism. After a learning curve, the technique appears to be safe and reliable. Preliminary data show promising results.

Synovial C-reactive protein as a marker for chronic periprosthetic infection in total hip arthroplasty.

The aim of this study was to assess the role of synovial C-reactive protein (CRP) in the diagnosis of chronic periprosthetic hip infection. We prospectively collected synovial fluid from 89 patients undergoing revision hip arthroplasty and measured synovial CRP, serum CRP, erythrocyte sedimentation rate (ESR), synovial white blood cell (WBC) count and synovial percentages of polymorphonuclear neutrophils (PMN). Patients were classified as septic or aseptic by means of clinical, microbiological, serum and synovial fluid findings. The high viscosity of the synovial fluid precluded the analyses in nine patients permitting the results in 80 patients to be studied. There was a significant difference in synovial CRP levels between the septic (n = 21) and the aseptic (n = 59) cohort. According to the receiver operating characteristic curve, a synovial CRP threshold of 2.5 mg/l had a sensitivity of 95.5% and specificity of 93.3%. The area under the curve was 0.96. Compared with serum CRP and ESR, synovial CRP showed a high diagnostic value. According to these preliminary results, synovial CRP may be a useful parameter in diagnosing chronic periprosthetic hip infection.