BACKGROUND:Complex repairs of radial meniscal tears have shown increased fixation strength compared to conventional sutures. A simplified 2-suture hybrid and a novel dual tie-grip repair with interconnected vertical mattress sutures spanning the tear were tested and compared to all-inside double-horizontal and tie-grip repairs. HYPOTHESIS:The dual tie-grip repair would increase the initial compression load across the tear and show the least cyclic displacement and highest failure strength. STUDY DESIGN:Controlled laboratory study. METHODS:A total of 40 porcine medial menisci were assigned to 4 repair groups: double-horizontal, hybrid, tie-grip, and dual tie-grip (10 per group). Results from tie-grip repairs were used to assess the effect of vertical mattress suture interconnection. After suture placement according to the described technique and fixation, the initial compressive load, stiffness, and relief displacement were measured. The repaired specimens underwent cyclic loading between 5 and 30 N over 1000 cycles (0.75 Hz), while cyclic stiffness and displacement were measured. Ultimate stiffness and load-to-failure were analyzed at 3.15 mm/s. RESULTS:Analysis of variance revealed that dual tie-grip and hybrid repairs showed higher initial compressive load and relief displacement than the other techniques, with dual tie-grip repair reaching the highest values for both metrics (load: 19.3 ± 2.3 N [P < .001]; displacement: 0.75 ± 0.19 mm [P < .001]). The double-horizontal repair had the lowest initial stiffness (P < .001). Cyclic displacement was lowest for the dual tie-grip repair and highest for the double-horizontal repair (both P < .001). All repaired specimens stiffened during cycling without intergroup differences. Analysis of covariance for stiffness over displacement revealed higher stabilization (P < .040) with dual tie-grip repair and reduced stabilization (P < .001) with double-horizontal repair. Despite comparable ultimate stiffness across groups, the dual tie-grip repair failed predominantly by suture rupture at the highest ultimate load (275.5 ± 26.2 N; P < .001), whereas the double-horizontal repair failed by tissue rupture the earliest (127.2 ± 15.9 N; P < .001). CONCLUSION:The dual tie-grip repair provided the highest initial compression across the radial meniscal tear, the lowest cyclic displacement, and the greatest load-to-failure among all techniques in a porcine cadaveric model. The simplified 2-suture hybrid repair showed higher initial compression than other repairs and comparable cyclic stability to the tie-grip repair. CLINICAL RELEVANCE:The dual tie-grip repair provided high compression across the radial tear and strong resistance to cyclic displacement. Future clinical series assessing differences in healing rates among different repair groups are warranted.

In modern knee arthroplasty, surgeons increasingly aim for individualised implant selection based on data-driven decisions to improve patient satisfaction rates. The identification of an implant design that optimally fits to a patient’s native kinematic patterns and functional requirements could provide a basis towards subject-specific phenotyping. The goal of this study was to achieve a first step towards identifying easily accessible and intuitive features that allow for discrimination between implant designs based on kinematic data. A squat-cycle was simulated on eight fresh frozen specimens mounted in a weight-bearing knee rig, each initially tested under native conditions, and then after implantation with four different implant types (CR/CS, MS, LS, and PS). The kinematic signals of these five configurations were compared to determine whether key differences between implants could be detected leveraging two methodological approaches: (1) statistical parametric mapping to directly compare waveforms and (2) simple paired t-tests to compare the three-dimensional coordinates of the functional centres of rotation determined using a previously published REference FRame Alignment Method (REFRAME). While statistical parametric mapping of the kinematic data revealed only small differences in certain comparisons (e.g. LS vs. PS, and MS vs. LS) under lenient statistical testing conditions, the application of REFRAME showed clear differences between implants (for all implant combinations except for CR/CS vs. LS), even under conservative statistical testing. Since for most implant combinations, significant differences in the centres of rotation were found using REFRAME, this approach could present a suitable tool for discriminating between the kinematics of different implant types. Preoperative assessment of joint kinematics, combined with this REFRAME application, could therefore provide a key approach for improved clinical selection of implant type.

Patellofemoral instability (PFI) is a multifactorial condition influenced by complex interactions between anatomical structures and dynamic stabilizers. Accurate assessment of mediolateral patellofemoral joint loading remains challenging, particularly during physiologically relevant joint angles simulated under controlled kinematic conditions. Anatomy-based individualized musculoskeletal models provide an in-silico approach to investigate these biomechanical parameters, such as the loading patterns. The purpose of this study was to develop individualized musculoskeletal knee models based on MRI-derived anatomical data from cadaveric specimens and to quantify the mediolateral component of the patellofemoral joint reaction force during a standardized, computer-driven squat simulation. Quadriceps muscle forces were estimated to assess the demand on dynamic stabilizers. : MRI scans from four cadaveric lower limbs were segmented to reconstruct the distal femur, proximal tibia, and patella. The resulting STL bone models of the femur, tibia, and patella were aligned to TLEM2 templates using anatomical landmarks in CATIA V5 and integrated into the AnyBody Modeling System via custom AnyScript routines. A predefined, computer generated squat motion consisting of asymmetric flexion–extension cycle between 0° and 90° at a constant, scripted angular velocity of 60°/s was applied using a kinematic driver. The original bodyweight-level loading conditions from the AnyBody squat model were retained; no external weights or EMG data were included. Patellofemoral joint reaction forces and quadriceps muscle forces were estimated using inverse dynamics calculations. The mediolateral patellofemoral joint reaction force increased with knee flexion in all models, reaching specimen-specific peaks ranging from 7 N/kg BW to 67 N/kg BW (maximum of 24 ± 25 N/kg BW). The model exhibiting a pronounced supratrochlear bony prominence (Dejour type B trochlear dysplasia) showed the highest lateral loading and quadriceps force. Muscle forces are reported as magnitudes. This study demonstrates that MRI-derived, individualized knee geometries can be integrated into a musculoskeletal simulation framework. This allows the investigation of how anatomical variation affects patellofemoral joint loading during a controlled, computer-generated squat motion. By integrating individualized knee anatomy into a validated simulation framework, our approach enables the in-silico analysis of anatomical risk factors—such as trochlear dysplasia and increased TT–TG distance—that are clinically relevant for patellofemoral instability. This method may support future biomechanical investigations and preoperative planning by providing reproducible, anatomy-driven insights into joint mechanics.

BACKGROUND:Osteochondrosis and osteonecrosis affect epiphyseal and apophyseal ossification centres and lead to structural changes in bone and cartilage. They differ in terms of aetiology, age and prognosis. Osteochondrosis dissecans and Osgood-Schlatter disease primarily affect adolescents, while spontaneous osteonecrosis of the knee (SONK/Ahlbäck's disease) predominantly occurs in older adults. OBJECTIVE:This article presents four clinical cases to illustrate typical manifestations, imaging diagnostics, and therapeutic strategies for osteochondronecrosis in children, adolescents and adults. CONCLUSION:Magnetic resonance imaging plays a key role in staging and guiding treatment decisions. While lesions in juveniles may resolve spontaneously, unstable or progressive cases often require surgical intervention. Ahlbäck's disease is associated with a poor prognosis and frequently necessitates joint replacement.

PURPOSE:The posterior cruciate-retaining (CR) design offers rotational freedom but risks abnormal kinematics and instability. The medial pivot (MP) design mimics native joint motion with a high-conformity medial and flat lateral interface. Within clinical studies, the MP design outclassed the CR design, but biomechanical studies are lacking. This study investigates the tibiofemoral and patellofemoral kinematics of both implant designs compared to native kinematics. METHODS:Eight fresh-frozen cadaveric knee specimens underwent total knee arthroplasty using MP and CR designs. Testing was performed in a dynamic knee rig simulating active knee flexion (30-130°) under muscle load. Biomechanical assessments included tibial rotation, tibiofemoral translation, patellar tilt/shift, patellofemoral contact/pressure patterns and quadriceps force. Functional regressions were used to analyse the effects of the component designs on the native situation. RESULTS:The MP design exhibited increased tibial rotation (130° flexion: MP 9.4° vs. CR 6.6°) and lateral anterior tibial translation during flexion (130° flexion: MP 25.8 mm vs. CR 22.6 mm). Both designs showed no significant differences in patellar tilt or shift and similar patellofemoral pressure (CR 3.2 MPa, MP 3.4 MPa) and contact patterns (CR 213.8 mm2 vs. MP 230.4 mm2). The MP design required lower quadriceps force, particularly in deep flexion (NS 452.6 N, CR 407.8 N and MP 367.3 N). CONCLUSION:The MP design provides a more native-like knee kinematic profile than the CR design, with a more pronounced MP motion pattern and reduced quadriceps loading. LEVEL OF EVIDENCE:Not applicable.

Instability remains one of the most common indications for revision after total knee arthroplasty. To gain a better understanding of how an implant will perform in vivo and support surgeons in selecting the most appropriate implant design for an individual patient, it is crucial to evaluate the implant constraint within clinically relevant ligament and boundary conditions. Therefore, this study investigated the constraint of three different implant designs (symmetrical implants with and without a post-cam mechanism and an asymmetrical medial-stabilized implant) under anterior–posterior shear forces and internal–external rotation moments at different flexion angles in human cadaveric knees using a six-degrees-of-freedom joint motion simulator. Both symmetrical designs showed no significant differences between the anterior–posterior range of motion of the medial and lateral condyles. In contrast, the medial-stabilized implant exhibited less anterior–posterior translation medially than laterally, without constraining the medial condyle to a fixed position. Furthermore, the post-cam implant design showed a significantly more posterior position of the femoral condyles in flexion compared to the other designs. The results show that despite the differences in ligament situations and individual implant positioning, specific characteristics of each implant design can be identified, reflecting the different geometries of the implant components.

Osteochondrosen und Osteonekrosen betreffen epiphysäre und apophysäre Ossifikationszentren und führen zu strukturellen Veränderungen von Knochen und Knorpel. Sie unterscheiden sich hinsichtlich Ätiologie, Alter und Prognose. Die Osteochondrosis dissecans (OD) und Morbus Osgood-Schlatter z. B. betreffen meist Jugendliche, während die spontane Osteonekrose (spontane Osteonekrose des Knies [SONK]/M. Ahlbäck) überwiegend bei älteren Erwachsenen auftritt. Anhand von 4 Fallbeispielen werden typische Manifestationen, bildgebende Diagnostik sowie therapeutische Strategien bei Osteochondronekrosen im Kindes‑, Jugend- und Erwachsenenalter dargestellt. Die Diagnostik, insbesondere mittels Magnetresonanztomographie (MRT), ist essenziell zur Stadieneinteilung und Therapiewahl. Während juvenile Läsionen teils spontan ausheilen, erfordern instabile oder progrediente Verläufe operative Maßnahmen. Der M. Ahlbäck zeigt meist eine ungünstige Prognose mit häufiger Notwendigkeit zur endoprothetischen Versorgung.

Objective: This study evaluated the effects of bony increased offset (BIO) and metallic augments (MAs) on primary reverse shoulder arthroplasty (RSA) baseplate stability in cadaveric specimens with variable bone densities. Methods: Thirty cadaveric specimens were analyzed in an imaging and biomechanical investigation. Computed tomography (CT) scans allowed for preoperative RSA planning and bone density analysis. Three correction methods of the glenoid were used: (1) corrective reaming with a standard baseplate, which served as the reference group (n = 10); (2) MA-RSA (n = 10); and (3) angled BIO-RSA (n = 10). Each augment group consisted of 10° (n = 5) and 20° (n = 5) corrections. Biomechanical testing included cyclic loading in an articulating setup, with optical pre- and post-cyclic micromotion measurements in a rocking horse setup. Results: There were no differences in bone density between groups based on CT scans (p > 0.126). The BIO-RSA group had higher variability in micromotion compared to the MA-RSA and reference groups (p = 0.013), and increased total micromotion compared to the reference group (p = 0.039). Both augmentations using 20° corrections had increased variance in rotational stability compared to the reference group (p = 0.043). Micromotion correlated with the subchondral bone density in the BIO-RSA group (r = −0.63, p = 0.036), but not in the MA-RSA (p > 0.178) or reference (p > 0.117) groups. Conclusions: Time-zero baseplate implant fixation is more variable with BIO-RSA and correlates with bone density. Corrections of 20° with either augmentation approach increase variability in rotational micromotion. The preoperative quantification of bone density may be useful before utilizing 20° of correction, especially when adding a bone graft in BIO-RSAs.

Purpose:Meniscal tears are common knee injuries and a major risk factor for secondary osteoarthritis. Recently, there has been a paradigm shift toward meniscal preservation, reflecting the meniscus's vital role. In this context, tissue engineering approaches such as the development of meniscal scaffolds have gained attention. However, to reduce the immune response and improve biocompatibility, decellularization of allografts, while preserving the histoarchitectural and meniscal properties, is essential. The current study aimed to evaluate the effectiveness of decellularization and its impact on the biomechanical properties of the human meniscus. Methods:Twenty-one human meniscus specimens were collected between July and December 2023 during total knee arthroplasty. Preoperative MRI was performed to verify meniscal integrity. The specimens were decellularized using a sodium dodecyl sulphate (SDS) protocol and compared to native meniscus samples in terms of cell count, assessed through hematoxylin and eosin staining, and biomechanical properties, specifically Young's modulus, measured using a universal testing machine (Zwick Z010). Results:The cell count in the decellularized menisci was 11 cells/mm² (SD = 13; 95% CI: 2-20), representing a significant reduction compared to the native meniscus samples, which had a cell count of 111 cells/mm² (SD = 42; 95% CI: 81-141; p < 0.01). Young's modulus of elasticity was 35.3 versus 36.8 MPa in the anterior region (p = 0.8), 32.6 versus 35.6 MPa in the central region (p = 0.7) and 36.5 versus 35.8 MPa in the posterior region (p = 0.9) for native versus decellularized samples, respectively. Conclusions:This study demonstrated that the modified SDS-based decellularization protocol effectively decellularizes the human meniscus. Moreover, the decellularized tissue retained biomechanical properties comparable to those of native meniscus tissue. Tissue decellularization is a promising technique in regenerative medicine, enabling the use of scaffolds for tissue repair, particularly in applications such as meniscus transplantation following meniscectomy. Level of Evidence:Level III, controlled laboratory study.

Despite its main function as abductor, the role of the supraspinatus as stabilizer and rotator cannot be neglected. A supraspinatus tear may not only influence humeral head rotation during abduction but also the strength and loading of the acting (intact) rotator cuff muscles. The purpose of this study was to investigate the effect of constrained humeral rotation and elevation on rotator cuff loading, strain and kinematics with intact and torn cuff conditions. Active humeral elevation until 30° was simulated in twelve fresh-frozen cadaver shoulders with free humeral rotation and blocked humeral rotation. The loading protocol was applied to the intact rotator cuff, and after a 50% and 100% wide (full-thickness) crescent-shaped (n = 6) and reverse L-shaped (n = 6) tears were created in the supraspinatus tendon. Constrained humeral rotation led to an increase in supraspinatus loading force and maximum supraspinatus strain for both tear shapes. Range of motion was significantly reduced in 7 of the 12 specimens due to blocked humeral rotation. In the 100% wide reverse L-shaped tear group, constrained rotation led to an anterior translation of humeral head, in contrast to the posterior translation observed with free rotation. Blocking humeral head rotation leads to an increase in supraspinatus and infraspinatus strains. According to its function as external rotator of the shoulder, the strain in the infraspinatus was higher at the beginning of abduction. However, small rotator cuff tears might not biomechanically result in increased humeral rotation, possibly because the load on the infraspinatus is compensated by the subscapularis. Basic Science Study; Biomechanics.

Purpose:The focus of this study was to evaluate the safety and efficacy of NOVOCART® 3D-treatment over a period of 36 months post-transplantation. Methods:This study was designed as a prospective, multicenter, single-arm, non-interventional investigation, aimed at evaluating the safety and efficacy of NOVOCART® 3D in patients with localized cartilage defects in the knee joint. 80 patients were enroled across 8 study centres and were followed post-operatively for a duration of 36 months. Safety assessments were conducted throughout the study period, while effectiveness data were evaluated pre-operatively and at 3, 12, 18, 24, and 36 months following cell transplantation, utilizing the International Knee Documentation Committee 2000 score (IKDC 2000). Results:Over the 3-year observation period among the 80 study patients, the incidence of surgery or product-related adverse events stood at 12.5%. Subjective scores according to IKDC 2000 demonstrated improvement, with a mean change from baseline of 30.5 ± 21.5 score points at 36 months. Similarly, the mean IKDC function score exhibited continuous enhancement, with a mean difference of 3.2 ± 3.0 score points. These changes from baseline were associated with nominally significant p-values from the 12-month mark onwards. The subgroup analysis revealed that only higher baseline scores and concurrent surgeries negatively impacted outcome parameters. Female sex, retro-patellar lesions, uncontained lesions, lesions with intralesional osteophytes or osteochondral defects did not exhibit any significant influence. Conclusion:The NISANIK study indicates the safety of NOVOCART® 3D treatment. Regarding effectiveness, patients in the study demonstrated a notable and progressively increasing mean improvement compared to their pre-operative condition. The study furthermore demonstrated that NOVOCART® is universally applicable across all age groups and Body Mass Index ranges, and it can also be effectively used in patients with female sex, larger lesions, retro-patellar lesions and in such having received bone-grafting without compromising the outcome, unlike related procedures. Level of Evidence:Level II, therapeutic, prospective cohort study.

Background: Recent biomechanical evidence for adjustable suture anchor (ASA)-based posterior medial meniscus root (PMMR) fixation has shown promising results compared with conventional transtibial pull-out repair (TPOR). However, ASA fixation has not been evaluated in human tissue to 100,000 cycles. Hypothesis: ASA repair would lead to increased primary fixation strength and less cyclic displacement than conventional TPORs. Study Design: Controlled laboratory study. Methods: A total of 32 human medial menisci were used, 8 of which were intact specimens and served as native controls. For the others, PMMR tears were created and repaired using 3 different techniques (n = 8 group). Two conventional PMMR repairs were prepared consisting of two No. 2 simple sutures (TSS) and two No. 2 sutures in a Mason-Allen (MA) configuration, all tied over a cortical button. The knotless ASA repair was fixed in MA with repair sutures tensioned at 120 N (MA-120). The repairs' initial force, stiffness, and relief displacement from the tensioned state toward repair unloading (2 N) were measured after fixation. All repair constructs were loaded for 100,000 cycles, with displacement and stiffness measured, and finally were pulled to failure. Results: The TPORs demonstrated similar primary fixation and cyclic loading behavior except for initial cyclic displacement (cycle 10). The ASA repair provided a higher initial repair load (P < .001) and stiffness (P < .001) with relief displacement similar to conventional TPORs. Lower initial cyclic displacement (P < .011; cycle 10) with overall higher repair stiffness (P < .011) resulted in significantly lower displacement (P < .001) throughout testing for ASA repair. Although both TPORs were completely loose after 100,000 cycles, the ASA repair achieved near-native dynamic meniscal stabilization. The TSS repair had lower overall ultimate load (P < .001) and ultimate stiffness (P < .023) compared with the ASA repair. All repairs had lower ultimate stiffness and loads than the native meniscus (P < .001). Conclusion: The ASA repair resulted in improved primary PMMR fixation that was stiffer with less cyclic displacement than conventional TPORs and approached that of the human meniscal function after 100,000 load cycles in a cadaveric model. However, all repair techniques had lower ultimate strength than the native human PMMR. Clinical Relevance: Knotless ASA meniscus root fixation resulted in higher tissue compression and less displacement in a cadaveric model; however, future clinical series with surveillance imaging will define the overall significance of healing rates.

Zusammenfassung Hintergrund Neben dem etablierten Doppelschlitten (bikondylärer Kniegelenksersatz [TKA]) hat sich, bei geeigneter Patientenselektion, der Monoschlitten (unikondylärer Kniegelenksersatz [UKA]) in der operativen Therapie der Gonarthrose bewährt. In klinischen Studien zeigt er überlegene funktionelle Ergebnisse bei geringeren Komplikationsraten. Im klinischen Alltag sind diese Vorteile, insbesondere bei jüngeren, sportlich und beruflich aktiven Patienten gegen den Nachteil einer erhöhten Revisionsrate abzuwiegen. Das Ergebnis einer ggf. früheren Revision erscheint hier relevant. Fragestellung Ziel dieser Studie war es, sowohl funktionelles Ergebnis als auch den Zeitraum bis zur Wiederaufnahme von Alltags-, beruflichen und sportlichen Aktivitäten nach Revision eines Mono- auf einen Doppelschlitten denen von primären Mono- und Doppelschlitten anhand einer Matched-Pair-Vergleichsanalyse gegenüberzustellen. Methodik Die Studie basierte auf einer Matched-Pair-Vergleichsanalyse zu zwei definierten Zeitpunkten und verglich stets 28 Patienten, die entweder die Revision eines Mono- auf einen Doppelschlitten, eine primäre Implantation eines Monoschlittens oder die eines Doppelschlittens erhielten. Die Patienten beantworteten im Rahmen eines standardisierten Follow-ups den Oxford Knee Score, den UCLA-Score, den Knee Society Score sowie den WOMAC-Score. Darüber hinaus wurden die postoperative Patientenzufriedenheit sowie die Wiederaufnahme von Alltags-, beruflichen und sportlichen Aktivitäten standardisiert erfasst und eine klinische Untersuchung durchgeführt. Ergebnisse Die vier untersuchten Funktions-Scores zeigten einen gemeinsamen Trend zugunsten der Monoschlitten, gefolgt von den primären Doppelschlitten und Revisionsdoppelschlitten. Die Unterschiede der Revisionsdoppelschlitten und der primären Doppelschlitten waren hierbei nicht signifikant. Allerdings lagen die Ergebnisse der konvertierten Monoschlitten 3,2 Jahre nach der letzten Operation signifikant unter denen der primären Monoschlitten. Die Rückkehr zur beruflichen und sportlichen Aktivität gelang nach Monoschlitten tendenziell am frühesten, gefolgt von Doppelschlitten und Revisionsgruppe. In allen Gruppen zeigte sich ein Trend zur Durchführung sog. Low-Impact-Sportarten. Diskussion Die funktionellen Ergebnisse eines konvertierten Monoschlittens zeigen sich denen der Primärimplantation auf Basis des 3‑Jahres-Follow-ups signifikant unterlegen. Die Rückkehr in Beruf, Sport und Alltag dauerte nach Revision tendenziell länger als nach Primärimplantation eines Mono- oder Doppelschlittens.

Anterior–posterior (AP) stability is an important measure of knee performance after total knee arthroplasty (TKA). To improve the stabilizing effect of implants designed to compensate for the loss of the cruciate ligaments, it is important to understand the tibiofemoral contact situation within the native ligamentous situation of the knee and how it changes after cruciate ligament resection. This in vitro study introduces a new approach to accurately measure the tibiofemoral kinematics in a six-degrees-of-freedom joint motion simulator by tracking landmark-based coordinate systems and their corresponding bone geometries. The tibiofemoral contact situation was investigated by projecting the medial and lateral flexion facet centers onto the tibial plateau under AP shear forces across various flexion angles in thirteen knees. Tests were conducted pre- and post-cruciate ligament resection. Post-cruciate ligament resection, the femoral condyles shifted closer to or even exceeded the posterior border of the tibial plateau, but only slightly closer to the anterior border. This study presents a new methodology for measuring the tibiofemoral kinematics that can be applied to multiple loading profiles. It provides a basis for further investigations, including passive or active muscle forces, to enhance the design of total knee protheses and improve surgical outcomes.

PurposeThe aim of this consensus project was to give recommendations regarding surgical treatment of the anterior cruciate ligament (ACL) injured patient.MethodsFor this consensus process, an expert, steering and rating group was formed. In an initial online meeting, the steering group, together with the expert group, formed various key topic complexes for which multiple questions were formulated. For each key topic, a structured literature search was performed by the steering group. The results of the literature review were sent to the rating group with the option to give anonymous comments until a final consensus voting was performed. Sufficient consensus was defined as 80% agreement.ResultsDuring this consensus process, 30 topics regarding the surgical management and technique of ACL reconstruction were identified. The literature search for each key question resulted in 30 final statements. Of these 30 final statements, all achieved consensus.ConclusionsThis consensus process has shown that surgical treatment of ACL injury is a complex process. Various surgical factors influence patient outcomes. The proposed treatment algorithm can be used as a decision aid for the surgeon.Level of EvidenceLevel V. For the first time, a consensus project was able to provide recommendations that could help standardise the surgical procedure in the treatment of ACL injuries. image

The first follow-up treatment recommendation from the DGOU's Clinical Tissue Regeneration working group dates back to 2012. New scientific evidence and changed framework conditions made it necessary to update the follow-up treatment recommendations after cartilage therapy. As part of a multi-stage member survey, a consensus was reached which, together with the scientific evidence, provides the basis for the present follow-up treatment recommendation. The decisive criterion for follow-up treatment is still the defect localisation. A distinction is made between femorotibial and patellofemoral defects. In addition, further criteria regarding cartilage defects are now also taken into account (stable cartilage edge, location outside the main stress zone) and the different methods of cartilage therapy (e. g. osteochondral transplantation, minced cartilage) are discussed. The present updated recommendation includes different aspects of follow-up treatment, starting with early perioperative management through to sports clearance and resumption of contact sports after cartilage therapy has taken place.

PURPOSE:To examine how augmentation of a rotator cuff repair with inflamed versus noninflamed bursal tissue affects tendon-to-bone healing in a rat model of rotator cuff repair. METHODS:A total of 136 Sprague-Dawley rats were randomly assigned to an inflamed or noninflamed bursal tissue application group. After detachment, the supraspinatus tendon was reattached with bursal tissue sewn onto the tendon-to-bone interface. The specimens were analyzed biomechanically 6 and at 7 weeks and immunohistologically at 1 and at 7 weeks after surgery. RESULTS:Immunohistological results showed no significant difference in the percentage of collagen type II in the tendon-to-bone interface at 1 (P = .87) and 7 weeks (P = .42) when using autologous noninflamed bursal tissue in comparison with inflamed bursal tissue specimens. The inflamed bursa group also showed no significant difference in collagen I to III quotient (P = .14) after surgery in comparison with noninflamed bursa groups after surgery. Biomechanical assessment showed that tendon stiffness (P = .87 inflamed versus noninflammed (resp.) P = .1) and the tendon viscoelasticity (P = .12 resp. P = .07) was the same after 6 and 7 weeks when we compared the inflamed bursa with the noninflamed bursa group. There was no significant difference (P = .8 resp. P = .87) in load to failure between in both inflamed and noninflamed bursa groups after 6 and 7 weeks. CONCLUSIONS:Autologous inflamed bursal tissue derived from the Achilles bursa and implanted to the tendon-to-bone interface after rotator cuff repair facilitates the same histologic and biomechanical healing response as using a noninflamed bursa interposition in rats. CLINICAL RELEVANCE:During augmentation of a rotator cuff repair, it is irrelevant whether the bursa tissue is inflamed.

Background: Anterior knee pain is a prevalent issue post total knee arthroplasty, often necessitating revision surgery. Various factors contribute to this complication, including patellar maltracking and excessive patellofemoral load. Kinematic alignment has emerged as an alternative, showing promising outcomes in clinical studies. However, its impact on patellofemoral biomechanics needs to be more adequately understood. This study compared the effects of kinematically versus mechanically aligned total knee arthroplasty on patellofemoral joint biomechanics. Methods: Eight fresh-frozen human knee specimens underwent biomechanical testing in a knee rig setup, performing an active weight-loaded knee joint flexion of 30–130°. After the testing of native kinematics, kinematically and mechanically aligned total knee arthroplasty was performed using a medial pivot implant design without patellar resurfacing. Quadriceps force, retropatellar peak pressure and the retropatellar contact area were measured during knee flexion using a patellar pressure-sensitive film. Patella kinematics (shift and tilt) was tracked using an optoelectrical measurement system. Functional regressions were used to determine the influence of the alignment on the kinematics and loading of the knee joint. Results: Kinematically aligned total knee arthroplasty resulted in reduced quadriceps force during knee flexion compared to mechanically aligned total knee arthroplasty. Retropatellar peak pressure, retropatellar contact area and patella kinematics did not vary between the alignments. Conclusions: Kinematic alignment offers potential benefits in reducing quadriceps force during knee flexion, which may mitigate anterior knee pain risk. Further research is needed to elucidate its effects in varying anatomical conditions and alignment strategies.

BACKGROUND:UKA is a well-established treatment option for anteromedial osteoarthritis of the knee, resulting in superior functional outcomes but also higher revision rates than TKA. This study aimed to compare the outcomes of UKA, TKA, UKA converted to TKA using identical standard implants and revised TKA to support clinical decision-making. METHODS:In this study, we retrospectively examined 116 patients who underwent UKA, 77 patients who received TKA, 28 patients whose UKA was converted to TKA using identical standard implants, and 21 patients who had a one-stage revision of TKA. The mean age at operation was 66.5 years (39-90 years), with a mean BMI of 28.8 kg/m2 (17.4-58.8) and a mean follow-up period of four years (0.9-9.9 years). We assessed various PROMs, including Oxford Knee Score, UCLA score, KSS score, and a modified WOMAC-Score as well as patient satisfaction and ability to resume daily activities, work, and sports. RESULTS:The highest patient satisfaction was seen in the UKA. All scores were significantly higher for UKA than for TKA, converted UKA, and revised TKA. None of the scores showed a significant inferiority of converted UKA to TKA. In the case of revision, two scores showed significantly better results for converted UKA than for revised TKA. CONCLUSIONS:Our results indicated that patients initially treated with UKA did not have significantly worse functional outcomes after conversion to TKA, given the use of identical standard implants. This highlights the effectiveness of UKA as a therapeutic option with outcomes superior to those of primary TKA and the importance of a bone-sparing procedure. Conversely, revision TKA is linked to poorer functional outcomes compared to both primary arthroplasties.

One of the major goals of total knee arthroplasty (TKA) is to restore the physiological function of the knee. In order to select the appropriate TKA design for a specific patient, it would be helpful to understand whether there is an association between passive knee kinematics intraoperatively and during complex activities, such as ascending stairs. Therefore, the primary objective of this study was to compare the anterior–posterior (AP) range of motion during simulated passive flexion and stair ascent at different conditions in the same knees using a six-degrees-of-freedom joint motion simulator, and secondary, to identify whether differences between TKA designs with and without a post-cam mechanism can be detected during both activities, and if one design is superior in recreating the AP translation of the native knee. It was shown that neither TKA design was superior in restoring the mean native AP translation, but that both CR/CS and PS TKA designs may be suitable to restore the individual native kinematic pattern. Moreover, it was shown that passive and complex loading scenarios do not result in exactly the same kinematic pattern, but lead to the same choice of implant design to restore the general kinematic behavior of the native individual knee.