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.

[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.

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.

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.

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.

[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.

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.

[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.

[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.

Suture anchor repair yields better biomechanical properties than transosseous sutures in ruptured quadriceps tendons.

PURPOSE: This human cadaveric study compares the biomechanical properties of quadriceps tendon repair with suture anchors and the commonly applied transosseous sutures. The hypothesis was that suture anchors provide at least equal results concerning gap formation and ultimate failure load compared with transosseous suture repair. METHODS: Thirty human cadaveric knees underwent tenotomy followed by repair with either 5.5-mm-double-loaded suture anchors [titanium (TA) vs. resorbable hydroxyapatite (HA)] or transpatellar suture tunnels using No. 2 Ultrabraid™ and the Krackow whipstitch. Biomechanical analysis included pretensioning the constructs with 20 N for 30 s and then cyclic loading of 250 cycles between 20 and 100 N at 1 Hz in a servohydraulic testing machine with measurement of elongation. Ultimate failure load analysis and failure mode analysis were performed subsequently. RESULTS: Tendon repairs with suture anchors yielded significantly less gap formation during cyclic loading (20th-250th cycle: TA 1.9 ± 0.1, HA 1.5 ± 0.5, TS 33.3 ± 1.9 mm, p < 0.05) and resisted significantly higher ultimate failure loads (TA 740 ± 204 N, HA 572 ± 67 N, TS 338 ± 60 N, p < 0.05) compared with transosseous sutures. Common failure mode was pull-out of the eyelet within the suture anchor in the HA group and rupture of the suture in the TA and TS group. CONCLUSION: Quadriceps tendon repair with suture anchors yields significantly better biomechanical results than the commonly applied transosseous sutures in this human cadaveric study. These biomechanical findings may change the future clinical treatment for quadriceps tendon ruptures. Randomised controlled clinical trials are desirable for the future. LEVEL OF EVIDENCE: Not applicable, controlled laboratory human cadaveric study.

[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.

Network dynamics predict improvement in working memory performance following donepezil administration in healthy young adults.

Attentional selection in the context of goal-directed behavior involves top-down modulation to enhance the contrast between relevant and irrelevant stimuli via enhancement and suppression of sensory cortical activity. Acetylcholine (ACh) is believed to be involved mechanistically in such attention processes. The objective of the current study was to examine the effects of donepezil, a cholinesterase inhibitor that increases synaptic levels of ACh, on the relationship between performance and network dynamics during a visual working memory (WM) task involving relevant and irrelevant stimuli. Electroencephalogram (EEG) activity was recorded in 14 healthy young adults while they performed a selective face/scene working memory task. Each participant received either placebo or donepezil (5mg, orally) on two different visits in a double-blinded study. To investigate the effects of donepezil on brain network dynamics we utilized a novel EEG-based Brain Network Activation (BNA) analysis method that isolates location-time-frequency interrelations among event-related potential (ERP) peaks and extracts condition-specific networks. The activation level of the network modulated by donepezil, reflected in terms of the degree of its dynamical organization, was positively correlated with WM performance. Further analyses revealed that the frontal-posterior theta-alpha sub-network comprised the critical regions whose activation level correlated with beneficial effects on cognitive performance. These results indicate that condition-specific EEG network analysis could potentially serve to predict beneficial effects of therapeutic treatment in working memory.

Biomechanical properties of femoral posterior cruciate ligament fixations.

PURPOSE: The success of reconstructions of the posterior cruciate ligament (PCL) mainly depends on the fixation strength of the tendon-bone interface. Reliable data about the mechanical characteristics of PCL fixation techniques are sparse. The aim of this study was to investigate the biomechanical properties of different femoral PCL fixation techniques. METHODS: Fresh human cadaver quadriceps (Q) and hamstring (H) tendons were harvested and fixed into porcine femora with a press-fit fixation suturing the tendon over a bone bridge (group A), a novel implant post-fixation (group B) or an interference screw fixation (group C). Each group consisted of 10 specimens. The constructs were cyclically stretched and eventually loaded until failure. Elongation during cyclic loading, stiffness, failure mode and maximum failure load was evaluated. RESULTS: Elongation during cyclical loading was significantly larger between the 1st and the 20th cycle than between the 20th and the 500th cycle in all groups (p < 0.05). Maximum failure load was 409 ± 71 (336-517) N in group QA, 456 ± 58 (347-510) N in group QB, 548 ± 116 (400-798) N in group QC, 472 ± 114 N (316-676 N) in group HA, 494 ± 98 N (371-668 N) in group HB and 498 ± 87 N (391-687 N) in group HC (significantly higher for QB compared to QA, p < 0.05). CONCLUSION: This is the first study investigating the biomechanical properties of femoral PCL fixations. Implant-free fixation techniques like press-fit or post-fixations are able to withstand equal biomechanical forces compared to interference screw fixation. The novel fixations described in this study can be considered as a reliable alternative for the reconstruction of PCL using either hamstring or quadriceps tendons.

[Computer-assisted systems in total knee arthroplasty. Useful aid or only additional costs]. / Computerassistenzsysteme in der Knieendoprothetik. Sinnvolle Hilfsmittel oder nur Mehraufwand.

BACKGROUND: The primary goal of computer-assisted surgery (CAS) in total knee arthroplasty is to increase the accuracy in terms of prosthesis positioning. In theory, this would lead to longer implant survival and a reduction of malpositioning. Thus, a better clinical outcome and lower revision rates would be expected. However, the necessary technical equipment represents significant additional effort and cost factors which are not included in the current diagnosis-related groups (DRG) system. OBJECTIVE: The objective of this article is a critical review of the current literature to examine whether these costs are reasonable by taking the additional benefits of the technology into account. METHODS: This review is based on a selective PubMed search on CAS and navigation in primary total knee arthroplasty. RESULTS: The current evidence base on CAS suggests that at least the primary outcome parameter, the improvement of the radiological alignment, is achieved by the technique. However, the claimed secondary effects are not yet proven. In particular, an improvement of clinical outcome and patient satisfaction has not been demonstrated so far. Furthermore, there is some evidence of increased complication rates by the use of CAS. CONCLUSION: Against this background and with respect to further cost-benefit analyses, the technology has to be reviewed critically. In particular, low-volume units do not seem to benefit from the use of CAS. However, the assessment of long-term effects is still pending.

Anatomic double-bundle ACL reconstruction restricts knee extension in knees with hyperextension.

PURPOSE: Double-bundle ACL reconstruction has been demonstrated to be at least as effective as single-bundle reconstruction in terms of restoring knee rotational and translational stability. Until now, the influence on knees with hyperextension has not been evaluated. It was the purpose of this study to evaluate whether double-bundle ACL reconstruction restricts extension in hyperextendable knees. METHODS: Hamstring tendon reconstructions of 10 human cadaveric knees with the ability of hyperextension (age: 48 ± 14 years) were performed as single bundle (SB) on one side and double bundle (DB) on the other side. A surgical navigation system (BrainLab, Germany) was used to assess the kinematics of each knee at the intact and reconstructed state. A difference with regard to the anterior-to-posterior translation (AP) and rotational stability at 30° of knee flexion, 90° of flexion and the hyperextension capability of each specimen was analysed. RESULTS: The difference in AP translation before and after the reconstruction was not significantly different in 30° and 90° of flexion (n.s). Both single- and double-bundle reconstructions restored the preoperative kinematics at 30° and 90° of knee flexion (n.s). The knee extension was 4° ± 1.8° with the intact ACL and 4° ± 1.7° after reconstruction in the SB group (n.s). The knee extension was 5° of hyperextension ± 1.1° with the intact ACL and 0° ± 0.4° after reconstruction in the DB group; the limitation of the extension was significantly larger in this group (p = 0.013). CONCLUSION: Both single- and double-bundle ACL reconstruction techniques are capable of restoring knee anteroposterior and rotational stability. Double-bundle reconstructions significantly reduce knee extension in knees with hyperextension capability. Care must be taken when using double-bundle techniques in patients with knee hyperextension as this procedure may limit the knee extension after double-bundle ACL reconstruction.

[Trauma sequalae after complex knee ligament injuries]. / Spätzustände nach komplexer Bandverletzung am Kniegelenk.

Complex ligament injuries can compromise a knee joint and residual conditions comprise stiffness (arthrofibrosis), instability, cartilage damage leading to osteoarthritis and bone deformity. Accurate diagnosis must address the direction and extent of the instability, the severity of any cartilage lesion and an analysis of the axis and bone deformity as well as important cofactors. Therapeutic options are adhesiolysis, ligament reconstruction, cartilage regeneration and axis correction. As a consequence patients mostly profit from the procedure but there is never a return to the functional level that existed before injury.