Valgus malalignment causes increased forces on a medial collateral ligament reconstruction under dynamic valgus loading: A biomechanical study.

PURPOSE: To investigate the forces on a medial collateral ligament (MCL) reconstruction (MCLR) relative to the valgus alignment of the knee. METHODS: Eight fresh-frozen human cadaveric knees were subjected to dynamic valgus loading at 400 N using a custom-made kinematics rig. After resection of the superficial medial collateral ligament, a single-bundle MCLR with a hamstring tendon autograft was performed. A medial opening wedge distal femoral osteotomy was performed and fixed with an external fixator to gradually adjust the alignment in 5° increments from 0° to 10° valgus. For each degree of valgus deformity, the resulting forces acting on the MCLR were measured through a force sensor and captured in 15° increments from 0° to 60° of knee flexion. RESULTS: Irrespective of the degree of knee flexion, increasing valgus malalignment resulted in significantly increased forces acting on the MCLR compared to neutral alignment (p < 0.05). Dynamic loading at 5° valgus resulted in increased forces on the MCLR at all flexion angles ranging between 16.2 N and 18.5 N (p < 0.05 from 0° to 30°; p < 0.01 from 45° to 60°). A 10° valgus malalignment further increased the forces on the MCLR at all flexion angles ranging between 29.4 N and 40.0 N (p < 0.01 from 0° to 45°, p < 0.05 at 60°). CONCLUSION: Valgus malalignment of the knee caused increased forces acting on the reconstructed MCL. In cases of chronic medial instabilities accompanied by a valgus deformity ≥ 5°, a realigning osteotomy should be considered concomitantly to the MCLR to protect the graft and potentially reduce graft failures. LEVEL OF EVIDENCE: Level III.

Collateral ligament strain is linearly related to coronal lower limb alignment: A biomechanical study.

PURPOSE: The purpose of this study was to analyse the influence of coronal lower limb alignment on collateral ligament strain. METHODS: Twelve fresh-frozen human cadaveric knees were used. Long-leg standing radiographs were obtained to assess lower limb alignment. Specimens were axially loaded in a custom-made kinematics rig with 200 and 400 N, and dynamic varus/valgus angulation was simulated in 0°, 30°, and 60° of knee flexion. The changes in varus/valgus angulation and strain within different fibre regions of the collateral ligaments were captured using a three-dimensional optical measuring system to examine the axis-dependent strain behaviour of the superficial medial collateral ligament (sMCL) and lateral collateral ligament (LCL) at intervals of 2°. RESULTS: The LCL and sMCL were exposed to the highest strain values at full extension (p < 0.001). Regardless of flexion angle and extent of axial loading, the ligament strain showed a strong and linear association with varus (all Pearson's r ≥ 0.98; p < 0.001) and valgus angulation (all Pearson's r ≥ -0.97; p < 0.01). At full extension and 400 N of axial loading, the anterior and posterior LCL fibres exceeded 4% ligament strain at 3.9° and 4.0° of varus, while the sMCL showed corresponding strain values of more than 4% at a valgus angle of 6.8°, 5.4° and 4.9° for its anterior, middle and posterior fibres, respectively. CONCLUSION: The strain within the native LCL and sMCL was linearly related to coronal lower limb alignment. Strain levels associated with potential ultrastructural damages to the ligaments of more than 4% were observed at 4° of varus and about 5° of valgus malalignment, respectively. When reconstructing the collateral ligaments, an additional realigning osteotomy should be considered in cases of chronic instability with a coronal malalignment exceeding 4°-5° to protect the graft and potentially reduce failures. LEVEL OF EVIDENCE: There is no level of evidence as this study was an experimental laboratory study.

Isometry of anteromedial reconstructions mimicking the deep medial collateral ligament depends on the femoral insertion.

PURPOSE: This study aimed to investigate the length change patterns of the native deep medial collateral ligament (dMCL) and potential anteromedial reconstructions (AMs) that might be added to a reconstruction of the superficial MCL (sMCL) to better understand the control of anteromedial rotatory instability (AMRI). METHODS: Insertion points of the dMCL and potential AM reconstructions were marked with pins (tibial) and eyelets (femoral) in 11 cadaveric knee specimens. Length changes between the pins and eyelets were then tested using threads in a validated kinematics rig with muscle loading of the quadriceps and iliotibial tract. Between 0° and 100° knee flexion, length change pattern of the anterior, middle and posterior part of the dMCL and simulated AM reconstructions were analysed using a rotary encoder. Isometry was tested using the total strain range (TSR). RESULTS: The tibiofemoral distance of the anterior dMCL part lengthened with flexion (+12.7% at 100°), whereas the posterior part slackened with flexion (-12.9% at 100°). The middle part behaved almost isometrically (maximum length: +2.8% at 100°). Depending on the femoral position within the sMCL footprint, AM reconstructions resulted in an increase in length as the knee flexed when a more centred position was used, irrespective of the tibial attachment position. Femoral positioning in the posterior aspect of the sMCL footprint exhibited <4% length change and was slightly less tight in flexion (min TSR = 3.6 ± 1.5%), irrespective of the tibial attachment position. CONCLUSION: The length change behaviour of potential AM reconstructions in a functionally intact knee is mainly influenced by the position of the femoral attachment, with different tibial attachments having a minimal effect on length change. Surgeons performing AM reconstructions to control AMRI would be advised to choose a femoral graft position in the posterior part of the native sMCL attachment to optimise graft length change behaviour. Given the high frequency of MCL injuries, sufficient restoration of AMRI is essential in isolated and combined ligamentous knee injuries. LEVEL OF EVIDENCE: There is no level of evidence as this study was an experimental laboratory study.

The anteromedial retinaculum in ACL-injured knees: An overlooked injury?

PURPOSE: The purpose of this study was to retrospectively analyse the pattern of injury to the medial knee structures in anterior cruciate ligament (ACL) injured patients. It was hypothesised that anteromedial injuries would be more common than posteromedial lesions. METHODS: One hundred and twenty subjects aged 18-25 years with a primary ACL injury were included. Patients were excluded if the time between injury and magnetic resonance imaging (MRI) was more than 28 days or if a knee dislocation or fracture was present. The MRIs were analysed with particular emphasis on injuries to the medial knee structures, menisci and bone bruise patterns. Injuries to the ligaments and anteromedial retinaculum (AMR) were graded according to severity, ranging from periligamentous oedema (grade I), partial fibre disruption of less or more than 50% (grade IIa or IIb) to complete tears (grade III). RESULTS: AMR injury was seen in 87 subjects (72.5%) on the coronal plane and in 88 (73.3%) on the axial plane, with grade III lesions observed in 27 (22.5%) and 29 knees (24.2%). Injuries to the superficial medial collateral ligament (sMCL), deep MCL (dMCL) and posterior oblique ligament (POL) were detected in 60 patients (50%), 93 patients (77.5%) and 38 patients (31.6%). However, grade III injuries to the POL were observed in only seven knees (5.8%). Medial meniscus injuries were associated with lesions of the sMCL and AMR (p < 0.05), while lateral meniscus injuries were significantly more common in patients with dMCL rupture (p < 0.05). CONCLUSION: Data from this study suggest that injuries to the AMR are much more common than posteromedial lesions in subjects with ACL injuries. LEVEL OF EVIDENCE: Level IV.

Treatment of cartilage defects in the patellofemoral joint with matrix-associated autologous chondrocyte implantation effectively improves pain, function, and radiological outcomes after 5-7 years.

INTRODUCTION: The aim of the present study was to evaluate midterm outcomes 5-7 years after matrix-associated autologous chondrocyte implantation (MACI) in the patellofemoral joint. MATERIALS AND METHODS: Twenty-six patients who had undergone MACI using the Novocart® 3D scaffold were prospectively evaluated. Clinical outcomes were determined by measuring the 36-Item Short-Form Health Survey (SF-36) and International Knee Documentation Committee (IKDC) scores and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) values preoperatively and 3, 6, and 12 months, and a mean of 6 years postoperatively. At the final follow-up, the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was evaluated. RESULTS: Twenty-two patients with 23 focal cartilage defects (19 patella and four trochlea) were available for the final follow-up. The mean defect size was 4.0 ± 1.9 cm2 (range 2.4-9.4 cm2). All clinical outcome scores improved significantly until 5-7 years after MACI (SF-36 score, 61.2 ± 19.6 to 83.2 ± 11.6; P = 0.001; IKDC score, 47.5 ± 20.6 to 74.7 ± 15.5; P < 0.001; and WOMAC, 29.8 ± 15.7 to 8.2 ± 10.3; P < 0.001). The mean MOCART score was 76.0 ± 11.0 at the final follow-up. Nineteen of the 22 patients (86.4%) were satisfied with the outcomes after 5-7 years and responded that they would undergo the procedure again. CONCLUSION: MACI in the patellofemoral joint demonstrated good midterm clinical results with a significant reduction in pain, improvement in function, and high patient satisfaction. These clinical findings are supported by radiological evidence from MOCART scores. LEVEL OF EVIDENCE: IV-case series.

Fragment size of lateral Hoffa fractures determines screw fixation trajectory: a human cadaveric cohort study.

BACKGROUND AND PURPOSE: Recommendations regarding fragment-size-dependent screw fixation trajectory for coronal plane fractures of the posterior femoral condyles (Hoffa fractures) are lacking. The aim of this study was to compare the biomechanical properties of anteroposterior (AP) and crossed posteroanterior (PA) screw fixations across differently sized Hoffa fractures on human cadaveric femora. PATIENTS AND METHODS: 4 different sizes of lateral Hoffa fractures (n = 12 x 4) were created in 48 distal human femora according to the Letenneur classification: (i) type I, (ii) type IIa, (ii) type IIb, and (iv) type IIc. Based on bone mineral density (BMD), specimens were assigned to the 4 fracture clusters and each cluster was further assigned to fixation with either AP (n = 6) or crossed PA screws (n = 6) to ensure homogeneity of BMD values and comparability between the different test conditions. All specimens were biomechanically tested under progressively increasing cyclic loading until failure, capturing the interfragmentary movements via motion tracking. RESULTS: For Letenneur type I fractures, kilocycles to failure (mean difference [∆] 2.1, 95% confidence interval [CI] -1.3 to 5.5), failure load (∆ 105 N, CI -83 to 293), axial displacement (∆ 0.3 mm, CI -0.8 to 1.3), and fragment rotation (∆ 0.5°, CI -3.2 to 2.1) over 5.0 kilocycles did not differ significantly between the 2 screw trajectories. For each separate subtype of Letenneur type II fractures, fixation with crossed PA screws resulted in significantly higher kilocycles to failure (∆ 6.7, CI 3.3-10.1 to ∆ 8.9, CI 5.5-12.3) and failure load (∆ 275 N, CI 87-463 to ∆ 438, CI 250-626), as well as, less axial displacement from 3.0 kilocycles onwards (∆ 0.4°, CI 0.03-0.7 to ∆ 0.5°, CI 0.01-0.9) compared with AP screw fixation. CONCLUSION: Irrespective of the size of Letenneur type II fractures, crossed PA screw fixation provided greater biomechanical stability than AP-configured screws, whereas both screw fixation techniques demonstrated comparable biomechanical competence for Letenneur type I fractures. Fragment-size-dependent treatment strategies might be helpful to determine not only the screw configuration but also the surgical approach.

Acromioclavicular and coracoclavicular ligamentous insertion distances depend on the scapular tilt and decrease with anterior direction of the inferior scapula angle.

PURPOSE: A variety of reconstruction techniques exist for the operative treatment of a ruptured acromioclavicular and coracoclavicular ligamentous complex. However, the complication rate remains high; between 5 and 89%. The intraoperative distance between the clavicle, acromion and coracoid is important for the refixation quality. In this study, the influence of scapular deflection on coracoclavicular and acromioclavicular distances was analysed. METHODS: The ligamentous insertions of 24 fresh-frozen human scapulae were exposed. The coracoclavicular and acromioclavicular ligaments were referenced and captured in a rigid body system using a three-dimensional (3D) measurement arm. The inferior angle of the scapula was manually pulled into maximum anterior and posterior deflection, simulating a patient positioning with or without dorsal scapular support, respectively. Based on the rigid body system, the distances between the ligamentous insertions were calculated. Statistical evaluation was performed by setting the distances in anterior deflection to 100% and considering the other distances relative to this position. RESULTS: The scapular deflection had a considerable impact on the distance between the ligamentous insertions. Concerning the conoid ligament, the mean distance was almost doubled when the inferior angle pointed posteriorly compared to anterior deflection (195.3 vs 100.0%; p = 0.028). The insertion of the acromioclavicular capsule also showed a significant association with the direction of deflection (posterior = 116.1% vs. anterior = 100%; p = 0.008). CONCLUSION: Dorsal support shifting the inferior angle of the scapula anteriorly reduces the distance between the ligamentous insertions. Therefore, a patient position on a shoulder table with posterior support of the scapula is recommended to reliability reduce the acromioclavicular joint.

The "Bankart knee": high-grade impression fractures of the posterolateral tibial plateau lead to increased translational and anterolateral rotational instability of the ACL-deficient knee.

PURPOSE: The aim of this biomechanical cadaver study was to evaluate the effects of high-grade posterolateral tibia plateau fractures on the kinematics of anterior cruciate ligament (ACL)-deficient joints; it was hypothesized that, owing to the loss of the integrity of the osseous support of the posterior horn of the lateral meniscus (PHLM), these fractures would influence the biomechanical function of the lateral meniscus (LM) and consequently lead to an increase in anterior translational and anterolateral rotational (ALR) instability. METHODS: Eight fresh-frozen cadaveric knees were tested using a six-degree-of-freedom robotic setup (KR 125, KUKA Robotics, Germany) with an attached optical tracking system (Optotrack Certus Motion Capture, Northern Digital, Canada). After the passive path from 0 to 90° was established, a simulated Lachman test and pivot-shift test as well as external rotation (ER) and internal rotation (IR) were applied at 0°, 30°, 60° and 90° of flexion under constant 200 N axial loading. All of the parameters were initially tested in the intact and ACL-deficient states, followed by two different types of posterolateral impression fractures. The dislocation height was 10 mm, and the width was 15 mm in both groups. The intraarticular depth of the fracture corresponded to half of the width of the posterior horn of the lateral meniscus in the first group (Bankart 1) and 100% of the meniscus width in the second group (Bankart 2). RESULTS: There was a significant decrease in knee stability after both types of posterolateral tibial plateau fractures in the ACL-deficient specimens, with increased anterior translation in the simulated Lachman test at 0° and 30° of knee flexion (p = 0.012). The same effect was seen with regard to the simulated pivot-shift test and IR of the tibia (p = 0.0002). In the ER and posterior drawer tests, ACL deficiency and concomitant fractures did not influence knee kinematics (n.s.). CONCLUSION: This study demonstrates that high-grade impression fractures of the posterolateral aspect of the tibial plateau increase the instability of ACL-deficient knees and result in an increase in translational and anterolateral rotational instability.

Small lateral meniscus tears propagate over time in ACL intact and deficient knees.

PURPOSE: To quantify propagation of small longitudinal tears in the lateral meniscus in ACL intact and deficient knees. METHODS: Using a robotic testing system, 5-Nm of external tibial torque + 5-Nm of valgus torque + 250-N of axial compression was applied to 14 fresh-frozen cadaveric knees while the knees were flexed from 30° to 90°. Knees were divided into two groups: intact (N = 8) and ACL deficient (N = 6). Kinematic data was recorded for four knee states: intact or ACL deficient knee, after posterior arthrotomy, meniscus tear at baseline, and after 500 cycles of the applied loading condition. RESULTS: Lateral meniscus tear length increased throughout the 500 cycles regardless of the ACL integrity (p < 0.001). Overall, an increase of 28.7% and 26.1% was observed in intact and ACL deficient knees, respectively. In intact knees, external tibial rotation increased with meniscus tear propagation at all flexion angles by up to 45.5% (p = 0.019). In contrast, knee kinematics in ACL deficient knees were not affected by meniscus tear propagation (n.s.). In ACL deficient knees, resultant forces in the lateral meniscus increased at all flexion angles by up to 116.5% (p = 0.012). No differences in forces were observed in the intact knees (n.s.). CONCLUSION: The data of this study show that small longitudinal tears in the lateral meniscus propagate significantly regardless of the integrity of the ACL and even after only 100 cycles of knee loading. The propagation of such tears altered kinematics and forces in the knee. Therefore, small, longitudinal lateral meniscus tears that are untreated in current clinical practices may propagate when loaded.

Combined posterolateral knee reconstruction: ACL-based injuries perform better compared to PCL-based injuries.

PURPOSE: To compare post-operative physical activity and return to work after combined posterolateral corner (PLC) reconstruction (PLC-R) in anterior cruciate ligament (ACL)- or posterior cruciate ligament (PCL)-based injuries. METHODS: Patients aged > 18 years undergoing PLC-R using the Larson technique combined with either ACL or PCL reconstruction were included. Outcome was evaluated retrospectively after a minimum follow-up of 24 months using Tegner Activity Scale, Activity Rating Scale (ARS), Knee Injury and Osteoarthritis Outcome Score (KOOS), work intensity according to REFA classification, and a questionnaire about type of occupation and time to return to work. RESULTS: A total of 32 patients (11 ACL-based injuries and 21 PCL-based injuries) were included. Mean follow-up was 56 ± 26 months in the ACL-based injury group and 59 ± 24 months in the PCL-based injury group. All patients in the ACL-based injury group and 91% of patients in the PCL-based injury group returned to sports activities. Comparing pre- and post-operative values, a significant deterioration of the Tegner Activity Scale and ARS was observed in the PCL-based injury group, whereas no significant change was observed in the ACL-based injury group. KOOS subscales were generally higher in the ACL-based injury with significant differences in the subscale sports and recreational activities. Patients with ACL-based injuries returned to work significantly earlier compared to patients with PCL-based injuries (11 ± 4 weeks vs. 21 ± 10 weeks, p < 0.05). CONCLUSION: High rates of return to sports and work can be expected after combined PLC-R in both ACL- and PCL-based injuries. However, deterioration of sports ability must be expected in PCL-based injuries. ACL-based injuries led to superior patient-reported outcomes and an earlier return to work, as compared to PCL-based injuries. LEVEL OF EVIDENCE: Level IV.

Medial collateral ligament reconstruction graft isometry is effected by femoral position more than tibial position.

PURPOSE: The purpose of this study was to examine the length change patterns of the native medial structures of the knee and determine the effect on graft length change patterns for different tibial and femoral attachment points for previously described medial reconstructions. METHODS: Eight cadaveric knee specimens were prepared by removing the skin and subcutaneous fat. The sartorius fascia was divided to allow clear identification of the medial ligamentous structures. Knees were then mounted in a custom-made rig and the quadriceps muscle and the iliotibial tract were loaded, using cables and hanging weights. Threads were mounted between tibial and femoral pins positioned in the anterior, middle, and posterior parts of the attachment sites of the native superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL). Pins were also placed at the attachment sites relating to two commonly used medial reconstructions (Bosworth/Lind and LaPrade). Length changes between the tibiofemoral pin combinations were measured using a rotary encoder as the knee was flexed through an arc of 0-120°. RESULTS: With knee flexion, the anterior fibres of the sMCL tightened (increased in length 7.4% ± 2.9%) whilst the posterior fibres slackened (decreased in length 8.3% ± 3.1%). All fibre regions of the POL displayed a uniform lengthening of approximately 25% between 0 and 120° knee flexion. The most isometric tibiofemoral combination was between pins placed representing the middle fibres of the sMCL (Length change = 5.4% ± 2.1% with knee flexion). The simulated sMCL reconstruction that produced the least length change was the Lind/Bosworth reconstruction with the tibial attachment at the insertion of the semitendinosus and the femoral attachment in the posterior part of the native sMCL attachment side (5.4 ± 2.2%). This appeared more isometric than using the attachment positions described for the LaPrade reconstruction (10.0 ± 4.8%). CONCLUSION: The complex behaviour of the native MCL could not be imitated by a single point-to-point combination and surgeons should be aware that small changes in the femoral MCL graft attachment position will significantly effect graft length change patterns. Reconstructing the sMCL with a semitendinosus autograft, left attached distally to its tibial insertion, would appear to have a minimal effect on length change compared to detaching it and using the native tibial attachment site. A POL graft must always be tensioned near extension to avoid capturing the knee or graft failure.

High prevalence of a deep lateral femoral notch sign in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus.

PURPOSE: To determine the prevalence of a deep lateral femoral notch sign (LFNS) in magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) and concomitant posterior root tears of the lateral meniscus (PLRT). METHODS: A retrospective chart review was conducted to identify all patients undergoing ACL reconstruction between 2016 and 2018. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: isolated ACL tear (ACL-Group), ACL tear with concomitant lateral meniscus tear not involving the posterolateral root (Meniscus-Group), and ACL tear with concomitant PLRT (PLRT-Group). Incidence and depth of a LFNS on preoperative MRI was compared between the three cohorts. RESULTS: 115 patients (mean age: 29.5 ± 11.3 years) were included in the study, with 58 patients (50.4%) assorted to the ACL-Group, 24 patients (20.9%) to the Meniscus-Group, and 33 patients (28.7%) to the PLRT-Group. The prevalence of a LFNS was significantly higher in the PLRT-Group (39.4%), when compared to the ACL- (5.2%) or Meniscus-Groups (25.0%; p < 0.001, respectively). Additionally, logistic regression analysis demonstrated that patients with PLRT were 5.3 times more likely to have a LFNS as compared to those without a lateral root tear (p < 0.001). CONCLUSION: In patients with ACL tears, the presence of a LFNS on preoperative MRI may be predictive for a PLRT. As the LFNS occurs in almost 40% of the patients with combined ACL tears and PLRT, the LFNS may be a useful secondary diagnostic finding in early MRI diagnostic. Identifying PLRT on MRI is clinically relevant, as it prevents misdiagnosis and facilitates surgical decision-making, thus avoiding subsequent delayed treatment. LEVEL OF EVIDENCE: Level IV.

Research productivity during orthopedic surgery residency correlates with pre-planned and protected research time: a survey of German-speaking countries.

PURPOSE: The purpose of this study was to identify modifiable factors associated with research activity among residents working in orthopedic surgery and traumatology. METHODS: Residents at 796 university-affiliated hospitals in Austria, Germany, and Switzerland were invited to participate. The online survey consisted of questions that ascertained 13 modifiable and 17 non-modifiable factors associated with the residents' current research activities. Responses of 129 residents were analyzed. Univariate linear regression was used to determine the association of individual factors with the current research activity (hours per week). The impact of significant non-modifiable factors (with unadjusted p values < 0.05) was controlled for using multivariate linear regression. RESULTS: The univariate analysis demonstrated six non-modifiable factors that were significantly associated with the current research activity: a University hospital setting (p < 0.001), an A-level hospital setting (p = 0.024), Swiss residents (p = 0.0012), the completion of a dedicated research year (p = 0.007), female gender (p = 0.016), and the department's size (p = 0.048). Multivariate regression demonstrated that the number of protected research days per year (p < 0.029) and the percentage of protected days, that were known 1 week before (p < 0.001) or the day before (p < 0.001), were significantly associated with a higher research activity. CONCLUSIONS: As hypothesized, more frequent and predictable protected research days were associated with higher research activity among residents in orthopedic surgery and traumatology. LEVEL OF EVIDENCE: III.

[A rare cause of an acutely locked knee joint: superior patellar dislocation]. / Eine seltene Ursache für das akut blockierte Kniegelenk: die superiore Patellaluxation.

The case of a 56-year-old male patient with locking of the knee in extension without trauma is presented. Patient history, clinical examination and radiographs confirmed a superior dislocation of the patella. Closed reduction led to full weight bearing with free range of motion without further complaints. Knowledge of this uncommon cause of a locked knee joint leads to immediate treatment avoiding complex imaging modalities, such as computed tomography (CT) or magnetic resonance imaging (MRI). No further treatment was necessary in the majority of the cases published in the literature.

[Current treatment standard for patella fractures in Germany]. / Aktueller Versorgungsstandard von Patellafrakturen in Deutschland.

BACKGROUND: The treatment of patella fractures is technically demanding. Although the radiological results are mostly satisfactory, this often does not correspond to the subjective assessment of the patients. The classical treatment with tension band wiring with K­wires has several complications. Fixed-angle plate osteosynthesis seems to be biomechanically advantageous. OBJECTIVE: Who is treating patella fractures in Germany? What is the current standard of treatment? Have modern forms of osteosynthesis become established? What are the most important complications? MATERIAL AND METHODS: The members of the German Society for Orthopedics and Trauma Surgery and the German Knee Society were asked to participate in an online survey. RESULTS: A total of 511 completed questionnaires were evaluated. Most of the respondents are specialized in trauma surgery (51.5%), have many years of professional experience and work in trauma centers. Of the surgeons 50% treat ≤5 patella fractures annually. In almost 40% of the cases preoperative imaging is supplemented by computed tomography. The classical tension band wiring with K­wires is still the preferred form of osteosynthesis for all types of fractures (transverse fractures 52%, comminuted fractures 40%). In the case of comminuted fractures 30% of the surgeons choose fixed-angle plate osteosynthesis. If the inferior pole is involved a McLaughlin cerclage is used for additional protection in 60% of the cases. DISCUSSION: The standard of care for patella fractures in Germany largely corresponds to the updated S2e guidelines. Tension band wiring is still the treatment of choice. Further (long-term) clinical studies are needed to verify the advantages of fixed-angle plates.

Promising clinical and magnetic resonance imaging results after internal bracing of acute posterior cruciate ligament lesions in multiple injured knees.

PURPOSE: The purpose of this study was to evaluate the clinical and radiological outcomes of acute posterior cruciate ligament (PCL) lesions in multiple injured knees that were surgically treated with internal bracing. METHODS: Acute complete PCL lesions in multiple injured knees with subsequent internal-bracing treatment within 21 days between 2014 and 2016 were eligible for inclusion. At final follow-up, patients were assessed with Tegner, Lysholm, and IKDC scores. PCL stability and healing were verified with KT-2000, stress radiography and magnetic resonance imaging (MRI). RESULTS: Fourteen patients [mean age 37.4 (± 17.8; SD) years] were evaluated after a mean follow-up of 19.9 (± 7.7; SD) months. Thirteen patients suffered complete lesions of the PCL with concomitant ligamentous injuries (Schenck I: six cases, Schenck III M: five cases, Schenck IV N: one case, Schenck V: one case). Median Tegner, mean Lysholm and mean IKDC scores at follow-up were 4 (2-7; interquartile range), 69.1 (± 16.6; SD) and 68.9 (± 18.1; SD) respectively. Posterior translation averaged 5.8 (± 2.2; SD) mm with the KT 2000 and stress radiography showed a mean posterior tibial translation of 5.5 (± 4.1; SD) mm in the side to side comparison. MRI showed adequate PCL healing. CONCLUSIONS: Internal bracing as treatment for acute PCL ruptures in multiple injured knees showed adequate restoration of posterior tibial translation in a single-centre study including 14 cases. LEVEL OF EVIDENCE: IV.

Neither lateral patellar facet nor patellar size are altered in patellofemoral unstable patients: a comparative magnetic resonance imaging analysis.

PURPOSE: It remains unclear if morphologic patterns of the patella itself predispose to patellar instability. This study examined established patellar landmarks in relation to the femoral condyle width to clarify differences of patellar morphologies in patellofemoral stable and unstable patients. METHODS: Magnetic Resonance Imaging of 50 subjects (20.7 ± 4.4 years; 17 males, 33 females) with patellofemoral instability (study group, SG) and 50 subjects (25.3 ± 5.8 years; 31 males, 19 females) with anterior cruciate ligament rupture (control group, CG) were analyzed. Corresponding patellar value indices (PW-I; LPF-I 1; LPF-I 2) in relation to the femoral condyle width (FCW) were evaluated after the measurement of absolute patellar dimension [patellar width (PW); direct length of the lateral patellar facet (LPF-1); projected length of the lateral patellar facet (LPF-2)]. The patellar shape according to Wiberg, trochlear dysplasia, patellar height, and tibial tubercle-trochlear groove (TT-TG) distance were determined. RESULTS: The SG showed a significantly longer absolute (LPF 2) (P = 0.041) and relative (LPF-I 1, LPF-I 2) (P < 0.001) lateral facet of the patella. No significant differences were evaluable for the relative patellar width (PW-I) (ns). A patellar shape type 3 (P = 0.001) as well as a higher position of the patella and TT-TG-distance (P < 0.001) were significantly more often present in the SG. CONCLUSION: There are several bony alterations associated with patellofemoral instability, but our data did not show a significantly smaller lateral patellar facet or relative patellar width that could facilitate a patellar dislocation. This helps surgeons, that are considering to surgically address the patella in cases of patellofemoral instability, to better understand its morphologic pattern. LEVEL OF EVIDENCE: III.

High short-term return to sports rate despite an ongoing healing process after acute meniscus repair in young athletes.

PURPOSE: Acute meniscus repair in young athletes is always a challenge due to the long rehabilitation process and time to return to sport (RTS). The purpose was to investigate signal alterations in short-term follow-up after acute meniscus repair on specific magnetic resonance imaging (MRI) scan sequences. It was hypothesized that (1) MRI signal changes over the first postoperative healing phase and represent a continuous healing process and (2) meniscus healing properties correlates with clinical outcomes and RTS. METHODS: Young athletes with traumatic meniscus lesion and arthroscopic meniscus repair within 6 weeks and available preoperative MRI were enrolled. Clinical examination, outcome scores (IKDC, KOOS, Lysholm Score, Tegner activity score) and RTS were surveyed preoperatively and 6 and 12 weeks and 6 months after surgery. Radiological follow-up examinations were performed 2, 4, 6, 12 weeks and 6 months after operation using a 3T-MRI. Evaluation was based on ISAKOS meniscus classification system, meniscus healing were classified according to Henning's criteria. RESULTS: At final follow-up (FU) 30 patients (28 month, 2 week) with a total of 35 meniscus tears (19 medial, 16 lateral) were included. Clinical scores improved significantly after surgery: IKDC Score (preOP: 39.4 ± 18.5, final FU: 78.8 ± 15.3) KOOS (preOP: 45.7 ± 22.1, final FU: 82.7 ± 12.5) and Lysholm Score (preOP: 42.8 ± 23.7, final FU: 84.4 ± 13.8) (p < 0.01). Tegner activity score showed a steadily increase to 4 (range 3-9) at 6 months but did not reached the pre-injury level of 6 (range 3-9). RTS rate was 100% whereof 44.8% reached their pre-injury level. MRI examination revealed a continuous healing process and menisci were classified as 55.9% healed, 35.3% partially healed and 8.8% non-healed at final FU. CONCLUSION: This study showed that MRI signal alterations of the meniscus steadily occur within the first 6 months postoperatively. MRI reveals an ongoing healing process at final FU that have to be carefully considered when RTS is discussed with high demanding patients. However, young athletes provide good clinical results and RTS rate even though MRI alterations are still present. LEVEL OF EVIDENCE: Therapeutic study, prospective case series, Level IV.

Insufficient consensus regarding circle size and bone loss width using the ratio-"best fit circle"-method even with three-dimensional computed tomography.

PURPOSE: Glenoid bone integrity is crucial for shoulder stability. The purpose of this study was to investigate a non-invasive method for quantifying bone loss regarding reliability and accuracy to detect glenoid bone deficiency in standard two-dimensional (2D) and three-dimensional (3D) computed tomography (CT) measurements at different time points. It was hypothesized that the diameter of the circle used would significantly differ between raters, rendering this method inaccurate and not allowing for an exact estimation of glenoid defect size. METHODS: Fifty-two shoulder CTs from 26 patients (26 2D-CTs; 26 3D-CTs) with anterior glenoid bone defects were evaluated by 6 raters at time 0 (T0) and at least 3 weeks after (T1) to assess the glenoid bone defect using the ratio method ("best fit circle"). Inter- and intra-rater differences concerning circle dimensions (circle diameter), measured width of bone loss and calculated percentage of bone loss (length-width-ratio) were compared in 2D- versus 3D-CT scans. The intraclass coefficient (ICC) was used to determine the inter- and intra-rater agreement. RESULTS: The mean circle diameter difference in 2D-CT was 2.0 ± 1.9 mm versus 1.8 ± 1.5 mm in 3D-CT, respectively (p < 0.01). Mean width of bone loss in 2D-CT was 1.9 ± 1.7 mm compared to 1.7 ± 1.5 mm in 3D-CT, respectively (p < 0.01). The mean difference of bone loss percentage was 5.1 ± 4.8% in 2D-CT and 4.8 ± 4.5% in 3D-CT (p < 0.01). No significant differences concerning circle diameter, bone loss width and bone loss percentage were detected comparing T0 and T1. Circle diameter, bone loss width and bone loss percentage measurements in 3D-CT were significantly smaller compared to 2D-CT at T0 and T1 (p < 0.01). Agreement (ICC) was fair to good for all indicators of circle diameter (range 0.76-0.83), bone loss width (range 0.76-0.86) and percentage of bone loss (range 0.85-0.91). Overall, 3D-CT showed superior agreement compared to 2D-CT. CONCLUSION: The ratio method varies in all glenoid parameters and is not valid for consistently quantifying glenoid bone defects even in 3D computed tomography. This must be taken into consideration when determining proper surgical treatment. The degree of glenoid bone loss alone should not be used to decide for or against a bony procedure. Rather, it is more important to define a defect size as "critical" and to also take other patient-specific factors into consideration so that the best treatment option can be undertaken. Application of the "best fitting circle" is a source of error when using the ratio method; therefore, care should be taken when measuring the circle diameter. LEVEL OF EVIDENCE: III.