Raul Mayr

Biomechanical Comparison of 2 Anterior Cruciate Ligament Graft Preparation Techniques for Tibial Fixation Adjustable-Length Loop Cortical Button or Interference Screw

Background: Cortical button fixation at the femoral side and interference screws within the tibial bone tunnel are widely used for anterior cruciate ligament graft fixation. Using a bone socket instead of a full tunnel allows cortical button fixation on the tibial side as well. If adjustable-length loop cortical button devices are used for femoral and tibial fixation, the tendon graft has to be secured with sutures in a closed tendon loop. The increased distance of fixation points and potential slippage of the tendon strands at the securing sutures might lead to greater risk of postoperative graft elongation when compared with conventional graft preparation with tibial interference screw fixation. Hypothesis: Compared with an anterior cruciate ligament graft with tibial adjustable-length loop cortical button fixation, a graft with tibial interference screw fixation will show less graft elongation during cyclic loading and lower ultimate failure loads. Study Design: Controlled laboratory study. Methods: Grafts with tibial adjustable-length loop cortical button fixation and grafts with tibial interference screw fixation were biomechanically tested in calf tibiae (n = 10 per group). Femoral fixation was equivalent for both groups, using an adjustable-length loop cortical button. Specimens underwent cyclic loading followed by a load-to-failure test. Results: Grafts with screw fixation showed significantly less initial elongation (cycles 1-5: 1.46 ± 0.26 mm), secondary elongation (cycles 6-1000: 1.87 ± 0.67 mm), and total elongation (cycles 1-1000: 3.33 ± 0.83 mm) in comparison with grafts with button fixation (2.47 ± 0.26, 3.56 ± 0.39, and 6.03 ± 0.61 mm, respectively) (P < .001). While pull-out stiffness was significantly higher for grafts with screw fixation (309.5 ± 33.2 vs 185.6 ± 16.4 N/mm) (P < .001), grafts with button fixation were able to withstand significantly higher ultimate failure loads (908 ± 74 vs 693 ± 119 N) (P < .001). Conclusion: Grafts with tibial adjustable-length loop cortical button fixation resulted in higher graft elongation during cyclic loading and showed higher ultimate failure loads in comparison with conventional graft preparation with tibial interference screw fixation at time zero. Clinical Relevance: The results of this biomechanical study suggest that grafts with tibial interference screw fixation provide better knee stability at time zero because of reduced graft elongation and greater stiffness in comparison with grafts with tibial adjustable-length loop cortical button fixation.

Revision anterior cruciate ligament reconstruction: an update

With the rising number of anterior cruciate ligament (ACL) reconstructions performed, revision ACL reconstruction is increasingly common nowadays. A broad variety of primary and revision ACL reconstruction techniques have been described in the literature. Recurrent instability after primary ACL surgery is often due to non-anatomical ACL graft reconstruction and altered biomechanics. Anatomical reconstruction must be the primary goal of this challenging revision procedure. Recently, revision ACL reconstruction has been described using double bundle hamstring graft. Successful revision ACL reconstruction requires an exact understanding of the causes of failure and technical or diagnostic errors. The purpose of this article is to review the causes of failure, preoperative evaluation, graft selection and types of fixation, tunnel placement, various types of surgical techniques and clinical outcome of revision ACL reconstruction.

The impact of coagulopathy on the outcome of traumatic epidural hematoma

PurposeTo evaluate the impact of trauma-associated coagulation disorders on the neurological outcome in patients with traumatic epidural hematoma undergoing surgical or non-surgical treatment. A retrospective analysis was performed using prospectively collected data in a consecutive patient series from a level 1 trauma center.MethodsEighty-five patients with traumatic epidural hematoma were identified out of 1,633 patients admitted to our emergency room with traumatic head injuries between October 2004 and December 2008. The following prospectively assessed parameters were analyzed: Glasgow Coma Scale, coagulopathy, presence of skull fractures, additional injuries, the Injury Severity Score, hematoma volume and thickness at admission, hematoma volume progression over time and neurologic symptoms. Furthermore, patients were grouped based on whether they had undergone surgical or non-surgical treatment of the epidural hematoma. Clinical outcome was determined according to the Glasgow Outcome Score (GOS) at hospital discharge.ResultsPatients with coagulopathy showed significantly lower GOS values compared to patients with intact blood coagulation. Initial and progressive hematoma volumes did not influence neurological outcome. Patients with multiple injuries did not show a worse outcome compared to those with isolated epidural hematoma. There was no difference in patient’s outcome after surgical or non-surgical treatment.ConclusionsPoor outcome after traumatic epidural hematoma was associated with coagulopathy. Progression of epidural hematoma volume was not associated with coagulopathy or with poor neurological outcome. Prospective studies are needed to confirm these results.

Subtalar arthrodesis stabilisation with screws in an angulated configuration is superior to the parallel disposition: a biomechanical study

PurposeThe purpose of this study was to compare the stability of two established screw configurations (SC) for subtalar arthrodesis using a cyclic loading model.MethodsEight paired human cadaver hindfoot specimens underwent subtalar arthrodesis with either parallel or angulated SC. The instrumented specimens were subjected to a cyclic loading protocol (1000 cycles: ±5 Nm rotation moment, 50 N axial force). The joint range of motion (ROM) was quantified before and after cyclic loading, in the three principal motion planes of the subtalar joint using pure bending moments of ±3 Nm.ResultsAfter instrumentation, the angulated SC showed significantly less mean ROM compared to the parallel SC in internal/external rotation (1.4° ± 2.2° vs. 3.3° ± 2.8°, P = 0.006) and in inversion/eversion (0.9° ± 1.4° vs. 1.5° ± 1.1°, P = 0.049). After cyclic loading, the angulated SC resulted in significantly less mean ROM compared to the parallel SC in internal/external rotation (3.3° ± 4.6° vs. 8.8° ± 8.0°, P = 0.006) and in inversion/eversion (1.9° ± 2.3° vs. 3.9° ± 3.9°, P = 0.017). No significant differences in the mean ROM were found between the angulated and parallel SC in dorsal extension/plantar flexion.ConclusionThe angulated SC resulted in decreased ROM in the subtalar arthrodesis construct after instrumentation and after cyclic loading compared to the parallel SC. The data from our study suggest that the clinical use of the angulated SC for subtalar arthrodesis might be superior to the parallel SC.

Effect of additional fixation in tibial plateau impression fractures treated with balloon reduction and cement augmentation

BACKGROUND Isolated tibial plateau impression fractures can be reduced through minimally invasive techniques using balloon inflation and cement augmentation. No evidence exists yet if an additional fixation at all and which method of fixation is necessary in the treatment of these fractures. The purpose of this study was to compare a locking plate and a screw raft for additional fixation after balloon reduction and cement augmentation in isolated tibial plateau impression fractures. Loss of reduction was subsequently analysed without additional fixation. METHODS Lateral tibial plateau impression fractures were created in eight matched pairs of human cadaveric tibiae. Reduction was performed using a balloon inflation system, followed by cement augmentation. Additional fixation was performed with a lateral locking plate or a screw raft (four 3.5-mm screws). Specimens were cyclically loaded at 20-240N, 20-360N and 20-480N. Subsequently, additional fixation was removed and the last cyclic interval (20-480N) repeated. Loss of reduction was assessed by measuring subsidence of the subchondral bone. FINDINGS Fractures treated with plate fixation exhibited less subsidence at higher loads compared with those treated with screw raft fixation (P<0.05). Loss of reduction significantly increased after removal of the additional fixation. INTERPRETATION This experimental study suggests that loss of reduction can be minimised by using locking plate fixation after balloon reduction and cement augmentation in the treatment of isolated tibial plateau impression fractures.

Ten-Year Results of Medial Open-Wedge High Tibial Osteotomy and Chondral Resurfacing in Severe Medial Osteoarthritis and Varus Malalignment:

Background: High tibial osteotomy (HTO) is a widely used treatment option for medial osteoarthritis and varus malalignment, especially in young patients with early osteoarthritis. Limited outcome data are available for this procedure in severe osteoarthritis, and no long-term data are available using newer implants. Purpose: To determine survivorship and functional results of medial open-wedge HTO combined with a chondral resurfacing (CR) procedure (abrasion plus microfracture) in severe medial osteoarthritis (Kellgren-Lawrence grade 3 and 4) and varus malalignment. Furthermore, factors that potentially influence the outcome were analyzed. Study Design: Case series; Level of evidence, 4. Methods: From September 2005 to December 2008, all cases of HTO (fixation with an angular-stable internal fixator) combined with CR were prospectively surveyed with regard to survival (Kaplan-Meier-method, not requiring arthroplasty) and functional outcome (subjective International Knee Documentation Committee [IKDC] score). Cartilage regeneration at the time of hardware removal, tibial bone varus angle (TBVA), pre- and postoperative mechanical medial proximal tibial angle (MPTA), and postoperative alignment were analyzed with regard to the result. Results: Seventy-nine knees were included (73 patients; mean age 50.9 ± 7.6 years). The follow-up rate was 90% at 10.0 ± 1.2 years (range, 8.3-12.1 years). Pre- and postoperative mechanical tibiofemoral axis were 9.6° ± 3.0° of varus and 0.6° ± 2.7° of valgus, respectively. Survival rate was 81.7% (95% CI, 72.5%-90.9%) at 10 years. Subjective IKDC score significantly improved from 44 ± 11 preoperatively to 70 ± 13 at one, 66 ± 15 at three, 66 ± 15 at five, and 65 ± 17 at ten years (P < .001 at any point of follow-up). Poor cartilage regeneration and low preoperative IKDC score (<40) were associated with decreased survival. High preoperative TBVA was associated with better and an overcorrected MPTA (>95°) with inferior functional outcome at final follow-up, respectively. Conclusion: Even in cases of severe medial osteoarthritis and varus malalignment, HTO in combination with a CR procedure is a good to excellent treatment option. The role of the CR procedure remains unclear. Although good results are obtained with overcorrected MPTA, long-term functional outcome is inferior.

Biomechanical Comparison of 2 Anterior Cruciate Ligament Graft Preparation Techniques for Tibial Fixation: Response

Background:Cortical button fixation at the femoral side and interference screws within the tibial bone tunnel are widely used for anterior cruciate ligament graft fixation. Using a bone socket instead of a full tunnel allows cortical button fixation on the tibial side as well. If adjustable-length loop cortical button devices are used for femoral and tibial fixation, the tendon graft has to be secured with sutures in a closed tendon loop. The increased distance of fixation points and potential slippage of the tendon strands at the securing sutures might lead to greater risk of postoperative graft elongation when compared with conventional graft preparation with tibial interference screw fixation.Hypothesis:Compared with an anterior cruciate ligament graft with tibial adjustable-length loop cortical button fixation, a graft with tibial interference screw fixation will show less graft elongation during cyclic loading and lower ultimate failure loads.Study Design:Controlled laboratory study.Methods:Grafts wi...

Biomechanical evaluation of a novel dynamic posterior cruciate ligament brace

BACKGROUND Use of a rigid brace or cast immobilization is recommended in conservative treatment or postoperative rehabilitation after a posterior cruciate ligament injury. To prevent the loss of knee joint function and muscle activity often associated with this, a flexible knee brace has been developed that allows an adjustable anteriorly directed force to be applied to the calf in order to prevent posterior tibial translation. The purpose of this biomechanical study was to evaluate the impact of this novel dynamic brace on posterior tibial translation after posterior cruciate ligament injury and reconstruction. METHODS A Telos stress device was used to provoke posterior tibial translation in seven human lower limb specimens, and stress radiographs were taken at 90° of knee flexion. Posterior tibial translation was measured in the native knees with an intact posterior cruciate ligament; after arthroscopic posterior cruciate ligament dissection with and without a brace; and after posterior cruciate ligament reconstruction with and without a brace. The force applied with the brace was measured using a pressure sensor. FINDINGS Posterior tibial translation was significantly reduced (P=0.032) after application of the brace with an anteriorly directed force of 50N to the knees with the dissected posterior cruciate ligament. The brace also significantly reduced posterior tibial translation after posterior cruciate ligament reconstruction in comparison with reconstructed knees without a brace (P=0.005). INTERPRETATION Posterior tibial translation was reduced to physiological values using this dynamic brace system that allows an anteriorly directed force to be applied to the calf.

Temporary postoperative treatment with compartment-unloading knee braces or wedge insoles does not improve clinical outcome after partial meniscectomy

PurposeTo investigate whether temporary postoperative compartment-unloading therapy after arthroscopic partial meniscectomy (APM)—with either knee braces or wedge insoles—leads to superior clinical outcome as compared to controls. This difference in clinical outcome was tested in the form of two knee scores, physical activity and general health outcome over the first postoperative year.MethodsSixty-three patients who underwent arthroscopic partial meniscectomy (APM) were randomized to one of the following three groups: 12 weeks postoperative knee compartment-unloading therapy with either a knee brace (brace group) or wedge insoles (insole group) or no specific postoperative therapy (control group). Patient-reported outcome was assessed with the International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC Score), the Knee Injury and Osteoarthritis Outcome Score (KOOS), the MARX score (physical activity) and the SF-12 (general health).ResultsSixty-three patients were available for analysis. Except for the SF-12 mental score, all other scores showed significant improvement over time. With regard to the hypotheses proposed, no significant group * time interactions were observed for any of the outcome parameters. This means that the group (i.e. the type of postoperative treatment) was not related to the degree of improvement of any of the scores.ConclusionsIt was concluded that 12 weeks of compartment-unloading therapy—with either a knee brace or wedge insoles—is ineffective with regard to clinical outcome after APM. This applies to the knee score outcome, physical activity and general health outcome over the first year following APM.Level of evidenceRandomized controlled trial, Level I.

Septic arthritis after arthroscopic posterior cruciate ligament and multi-ligament reconstructions is rare and can be successfully treated with arthroscopic irrigation and debridement: analysis of 866 reconstructions

PurposeThe purpose of this study was to determine the incidence of septic arthritis following arthroscopic posterior cruciate ligament (PCL) and multi-ligament reconstructions, and to evaluate a treatment regime with sequential arthroscopic irrigation and debridement procedures combined with antibiotic therapy that is focused on retention of the graft.MethodsBetween 2004 and 2016 a total of 866 PCL reconstructions and multi-ligament reconstructions were performed at our institution (408 isolated PCL reconstructions, 458 combined reconstructions). Medical charts of all cases were retrospectively reviewed with regard to the occurrence of septic complications. These cases were analysed with special focus on clinical management, number of reoperations and if the grafts were retained. Further, microbiological findings, postoperative clinical course and available clinical outcome data were evaluated.ResultsFour cases of septic arthritis (0.5%) were identified (follow-up rate 96.5%): two following isolated PCL reconstruction (0.5%), and two following multi-ligament reconstruction (0.4%), respectively. Septic arthritis was successfully treated in all cases with a mean of 2.5 ± 2.4 irrigation and debridement procedures (1–6). In one case of isolated PCL reconstruction, the graft was resected within the fifth irrigation and debridement due to septic loosing of the femoral fixation. All other grafts were retained. With regard to the outcome, all patients were subjectively satisfied with good stability (stress radiographs) in cases of retained grafts.ConclusionPostoperative septic arthritis after arthroscopic PCL and complex knee ligament reconstructions is a rare but serious complication. Arthroscopic graft-retaining treatment is recommended, as it is established in ACL surgery. Graft retention can be expected in the majority of the cases.Level of evidenceCase series, Level 4.