Christoph Domnick

Intra-articular tibial plateau fracture characteristics according to the “Ten segment classification”

BACKGROUND Currently existing classifications of tibial plateau fractures do not help to guide surgical strategy. Recently, a segment-based mapping of the tibial plateau has been introduced in order to address fractures with a fracture-specific surgical approach. The goal of the present study was to analyze incidence and fracture specifics according to a new 10-segment classification of the tibial plateau. METHODS A total of 242 patients with 246 affected knees were included (124 females, 118 males, mean age 51.9±16.1years). Fractures were classified according to the OTA/AO classification. Fracture pattern was analyzed with respect to a 10-segment classification based on CT imaging of the proximal tibial plateau 3cm below the articular surface. RESULTS 161 Patients suffered an OTA/AO type 41-B and 85 patients an OTA/AO type 41-C tibial plateau fracture. Females had an almost seven times higher risk to suffer a fracture due to low-energy trauma (OR 6.91, 95% CI (3.52, 13.54), p<0.001) than males. In 34% of the patients with affection of the medial tibial plateau, a fracture comminution, primarily due to low-energy trauma (p<0.001), was observed. In type B fractures, the postero-latero-lateral (65.2%), the antero-latero-lateral (64.6%) and the antero-latero-central (60.9%) segment were most frequently affected. Every second type C fracture showed an unique fracture line and zone of comminution. The tibial spine was typically involved (89.4%). A typical fracture pattern of high-energy trauma demonstrated a zone of comminution of the lateral plateau and a split fracture in the medial plateau. The most frequently affected segments were the postero-latero-central (85.9%), postero-central (84.7%), and antero-latero-central (78.8%) segment. CONCLUSION Posterior segments were the most frequently affected in OTA/AO type B and C fractures. Acknowledging the restricted visibility of posterior segments, whose reduction and fixation is crucial for long-term success, our findings implicate the use of posterior approaches more often in the treatment of tibial plateau fractures. Also, low-energy trauma was identified as an important cause for tibial plateau fractures.

MPFL reconstruction using a quadriceps tendon graft Part 1: Biomechanical properties of quadriceps tendon MPFL reconstruction in comparison to the Intact MPFL. A human cadaveric study

BACKGROUND The aim of this study was to analyze the structural properties of the original MPFL and to compare it to a MPFL-reconstruction-technique using a strip of quadriceps tendon. METHODS In 13 human cadaver knees the MPFLs were dissected protecting their insertion at the patellar border. The MPFL was loaded to failure after preconditioning with 10 cycles in a uniaxial testing machine evaluating stiffness, yield load and maximum load to failure. In the second part Quadriceps-MPFL-reconstruction was performed and tested in a uniaxial testing machine. Following preconditioning, the constructs were cyclically loaded 1000 times between 5 and 50 N measuring the maximum elongation. After cyclic testing, the constructs have been loaded to failure measuring stiffness, yield load and maximum load. For statistical analysis a repeated measures (RM) one-way ANOVA for multiple comparisons was used. The significance was set at P<0.05. RESULTS During the load to failure tests of the original MPFL the following results were measured: stiffness 29.4 N/mm (+9.8), yield load 167.8 N (+80) and maximum load to failure 190.7 N (+82.8). The results in the QT-technique group were as follows: maximum elongation after 1000 cycles 2.1 mm (+0.8), stiffness 33.6 N/mm (+6.8), yield load 147.1 N (+65.1) and maximum load to failure 205 N (+77.8). There were no significant differences in all tested parameters. CONCLUSIONS In a human cadaveric model using a strip of quadriceps-tendon 10 mm wide and 3mm deep, the biomechanical properties match those of the original MPFL when tested as a reconstruction. CLINICAL RELEVANCE The tested QT-technique shows sufficient primary stability with comparable biomechanical parameters to the intact MPFL.

Comparison of Knee Kinematics After Single-Bundle Anterior Cruciate Ligament Reconstruction via the Medial Portal Technique With a Central Femoral Tunnel and an Eccentric Femoral Tunnel and After Anatomic Double-Bundle Reconstruction: A Human Cadaveric Study

Background: Anatomic femoral tunnel placement in anterior cruciate ligament (ACL) reconstruction is considered to be a key to good primary stability of the knee. There is still no consensus on whether a centrally placed single bundle in the anatomical femoral footprint can compare with anatomic double-bundle (DB) reconstruction. Purpose/Hypothesis: The purpose of this study was to determine knee kinematics after single-bundle ACL reconstruction via the medial portal technique using 2 different femoral tunnel positions and to compare results with those of the anatomic DB technique. The hypotheses were that (1) single-bundle reconstruction using the medial portal technique with a centrally placed femoral tunnel relative to the native footprint (SB-central technique) would more closely restore intact knee kinematics compared with the same reconstruction technique with an eccentric femoral tunnel drilled in the anteromedial bundle footprint (SB-AM technique) and (2) DB reconstruction would result in superior kinematics compared with the SB-central technique. Study Design: Controlled laboratory study. Methods: Knee kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force-moment sensor system. Kinematics in simulated pivot-shift and 134-N anterior tibial loading tests were determined in different conditions within the same specimen: (1) intact ACL, (2) deficient ACL, (3) SB-AM, (4) SB-central, and (5) DB. Results: All reconstruction techniques significantly reduced anterior tibial translation (ATT) compared with a deficient ACL at 0°, 15°, 30°, 60°, and 90° in the anterior tibial loading test (P < .01, repeated-measures analysis of variance) and at 0°, 15°, and 30° in the simulated pivot-shift test (P < .001). There were no significant differences in the SB-central group and the DB group compared with the intact ACL. Reconstruction in the SB-AM group resulted in significantly increased ATT compared with the intact ACL in near-to-extension angles in both tests (0°, 15°, and 30°; P < .01). SB-central and DB reconstructions both resulted in significantly reduced ATT, in some tests at ≤30°, compared with SB-AM reconstruction (P < .05). No significant differences between the SB-central and DB groups were found (P > .05). Conclusion: The SB-central technique restored intact knee kinematics more closely than did SB-AM reconstruction at time zero. There were no differences in knee kinematics between the DB and SB-central techniques. Clinical Relevance: Anatomic single-bundle ACL reconstruction provides similar knee kinematics as anatomic double-bundle reconstruction.

Should the Ipsilateral Hamstrings Be Used for Anterior Cruciate Ligament Reconstruction in the Case of Medial Collateral Ligament Insufficiency? Biomechanical Investigation Regarding Dynamic Stabilization of the Medial Compartment by the Hamstring Muscles:

Background: Semitendinosus and gracilis muscles are frequently harvested for autologous tendon grafts for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of these hamstring muscles in cases of insufficiency of the medial collateral ligament (MCL). Hypotheses: First, both the semitendinosus and gracilis muscles can actively stabilize the joint against valgus moments in the MCL-deficient knee. Second, the stabilizing influence of these muscles decreases with an increasing knee flexion angle. Study Design: Controlled laboratory study. Methods: The kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force moment sensor system and an optical tracking system. The knee kinematics under 5- and 10-N·m valgus moments were determined in the different flexion angles of the (1) MCL-intact and (2) MCL-deficient knee using the following simulated muscle loads: (1) 0-N (idle) load, (2) 200-N semitendinosus (ST) load, and (3) 280-N (200/80-N) combined semitendinosus/gracilis (STGT) load. Results: Cutting the MCL increased the valgus angle under all tested conditions and angles compared with the MCL-intact knee by 4.3° to 8.1° for the 5-N·m valgus moment and 6.5° to 11.9° for the 10-N·m valgus moment (P < .01). The applied 200-N simulated ST load reduced the valgus angle significantly at 0°, 10°, 20°, and 30° of flexion under 5- and 10-N·m valgus moments (P < .05). At 0°, 10°, and 20° of flexion, these values were close to those for the MCL-intact joint under the respective moments (both P > .05). The combined 280-N simulated STGT load significantly reduced the valgus angle in 0°, 10°, and 20° of flexion under 5- and 10-N·m valgus moments (P < .05) to values near those for the intact joint (5 N·m: 0°, 10°; 10 N·m: 0°, 10°, 20°; P > .05). In 60° and 90° of flexion, ST and STGT loads did not decrease the resulting valgus angle of the MCL-deficient knee without hamstring loads (P > .05 vs deficient; P = .0001 vs intact). Conclusion: In this human cadaveric study, semitendinosus and gracilis muscles successfully stabilize valgus moments applied to the MCL-insufficient knee when the knee is near extension. Clinical Relevance: In the valgus-unstable knee, these data suggest that the hamstring muscles should be preserved in (multi-) ligament surgery when possible.

Biomechanics of the anterior cruciate ligament: Physiology, rupture and reconstruction techniques

The influences and mechanisms of the physiology, rupture and reconstruction of the anterior cruciate ligament (ACL) on kinematics and clinical outcomes have been investigated in many biomechanical and clinical studies over the last several decades. The knee is a complex joint with shifting contact points, pressures and axes that are affected when a ligament is injured. The ACL, as one of the intra-articular ligaments, has a strong influence on the resulting kinematics. Often, other meniscal or ligamentous injuries accompany ACL ruptures and further deteriorate the resulting kinematics and clinical outcomes. Knowing the surgical options, anatomic relations and current evidence to restore ACL function and considering the influence of concomitant injuries on resulting kinematics to restore full function can together help to achieve an optimal outcome.

Partial proximal tibia fractures

Partial tibial plateau fractures may occur as a consequence of either valgus or varus trauma combined with a rotational and axial compression component. High-energy trauma may result in a more complex and multi-fragmented fracture pattern, which occurs predominantly in young people. Conversely, a low-energy mechanism may lead to a pure depression fracture in the older population with weaker bone density. Pre-operative classification of these fractures, by Müller AO, Schatzker or novel CT-based methods, helps to understand the fracture pattern and choose the surgical approach and treatment strategy in accordance with estimated bone mineral density and the individual history of each patient. Non-operative treatment may be considered for non-displaced intra-articular fractures of the lateral tibial condyle. Intra-articular joint displacement ⩾ 2 mm, open fractures or fractures of the medial condyle should be reduced and fixed operatively. Autologous, allogenic and synthetic bone substitutes can be used to fill bone defects. A variety of minimally invasive approaches, temporary osteotomies and novel techniques (e.g. arthroscopically assisted reduction or ‘jail-type’ screw osteosynthesis) offer a range of choices for the individual and are potentially less invasive treatments. Rehabilitation protocols should be carefully planned according to the degree of stability achieved by internal fixation, bone mineral density and other patient-specific factors (age, compliance, mobility). To avoid stiffness, early functional mobilisation plays a major role in rehabilitation. In the elderly, low-energy trauma and impression fractures are indicators for the further screening and treatment of osteoporosis. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160067. Originally published online at www.efortopenreviews.org

Kinematics of the posterolateral corner of the knee: A human cadaveric cutting study.

Aims and Objectives: The posterolateral corner of the knee consists of different structures, which contribute to instability when damaged after injury or within surgery. Knowing the kinematic influences may help to improve clinical diagnostics and surgical techniques. The purpose was to determine static stabilizing effects of the posterolateral corner by dissecting stepwise all fibers and ligaments (the arcuat complex, AC) connected with the popliteus tendon (PLT) and the influence on lateral stability in the lateral collateral ligament (LCL) intact-state. Materials ans Methods: Kinematics were examined in 13 fresh-frozen human cadaveric knees using a robotic/UFS testing system with an optical tracking system. The knee kinematics were determined for 134 N anterior/posterior loads, 10 Nm valgus/varus loads and 5 Nm internal/external rotational loads in 0°, 20°, 30°, 60° and 90° of knee flexion. The posterolateral corner structures were consecutively dissected: The I.) intact knee joint, II.) with dissected posterior cruciate ligament, III.) meniscofibular/-tibial fibers, IV.) popliteofibular ligament, V.) popliteotibial fascicle (last structure of static AC), VI.) PLT and VII.) LCL. Results: The external rotation angle increased significantly by 2.6° to 7.9° (P<.05) in 0° to 90° of knee flexion and posterior tibial translation increased by 2.9 mm to 5.9 mm in 20° to 90° of knee flexion (P<.05) after cutting the AC/PLT structures (with intact LCL) in contrast to the PCL deficient knee. Differences between dissected static AC and dissected PLT were only found in 60° and 90° external rotation tests (by 2.1° and 3.1°; P<.05). In the other 28 kinematic tests, no significant differences between PLT and AC were found. Cutting the AC/PLT complex did not further decrease varus, valgus or anterior tibial stability in any flexion angle in comparison to the PCL dissected state. Conclusion: The arcuat complex is an important static stabilizer for external rotatory and posterior tibial loads of the knee, even in the lateral collateral ligament intact-state. After dissecting the major parts of the arcuat complex, the static stabilizing function of the popliteus tendon is lost. The arcuat complex has no varus-stabilizing function in the LCL-intact knee. The anatomy and function of these structures for external-rotational and posterior-translational stabilization should be considered for clinical diagnostics and when performing surgery in the posterolateral corner.

Can we use the ipsilateral Hamstrings for ACL Reconstruction in case of medial collateral ligament insufficiency

Aims and Objectives: Semitendinosus and gracilis muscles (hamstring muscles) are frequently harvested autologous tendon grafts of the knee e.g. for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of these muscles in case of insufficiency of the medial collateral ligament (MCL). Hypotheses: First, both the semitendinosus and the gracilis muscles can actively stabilize the joint against valgus stress in the medial collateral unstable knee. Second, this stabilizing influence of these muscles decreases with increasing flexion angle Meterials and Methods: Kinematics were examined in ten fresh-frozen human cadaveric knees using a robotic/UFS testing system and an optical tracking system. The knee kinematics under 5 Nm and 10 Nm valgus stress were determined in the a) MCL intact and b) MCL deficient knee in different flexion angles, respectively using the following simulated muscle loads: 1) 0 N (Idle), 2) 200 N semitendinosus load (ST) and 3) 280 N combined semitendinosus and gracilis load (STGT). Results: Cutting the MCL increased valgus angle under all tested conditions and angles in contrast to the MCL intact knee by 4.3-8.1 degrees for 5 Nm, 6.5-11.9 degrees for 10 Nm valgus torque; P<.01; RM-ANOVA). Applied 200 N simulated ST load reduced the valgus angle significantly in 0°, 10°, 20° and 30° of flexion under 5 Nm and 10 Nm (P< .05) valgus stress. In 0°, 10° and 20° these values were close to the MCL intact joint under the respective torque (both P >.05). The combined 280 N simulated STGT load reduced significantly valgus angle in 0°, 10° and 20° of flexion under 5 Nm and 10 Nm of valgus stress (P< .05) to values near the intact joint (5 Nm: 0°, 10°; 10 Nm: 0°, 10°, 20° - P >.05). In 60° and 90° of flexion ST and STGT loads could not decrease resulting valgus angle of the MCL deficient knee (without hamstring load; P>.05 or valgus increase P<.05). Conclusion: In this human cadaveric study semitendinosus and gracilis muscles can successfully stabilize against valgus stress in the MCL insufficient knee in near-to-extension flexion angles. In the valgus-unstable knee, hamstring muscles should be preserved in (multi-) ligament surgery, but also in joint arthroplasty and osteosynthesis if possible.

Trends and incidence of cartilage, ligament- and arthroscopic surgery: Analysis of German in-patient records 2005-2013

Aims and Objectives: Apart from some international cruciate ligament and arthroplasty register data, little epidemiological baseline facts are known about many joint surgical procedures. The German Federal Statistical Office collects the encoded population-based data of all medical in-patient procedures performed in Germany. The purpose of this study was to analyze these data to assess epidemiological trends and incidences in joint surgery. Materials and Methods: The comprehensive database of medical procedures of the German DRG system between 2005 and 2013, including 154 million anonymized in-patient records, were screened and analyzed for joint surgical procedures. Results: Trends of incidence rates of many joint surgical procedures have been detected. There was an increasing incidence of arthroscopic procedures in relation to the open procedures. Anterior cruciate ligament reconstruction or repair has a high incidence of 46 per 100,000 person-years, most popular grafts were hamstring tendon (90%) and patellar tendon (6.3%) autografts (2013). Conclusion: This is the first baseline epidemiological data out of 154 million in-patient records in Germany including joint and ligament surgical procedures with a focus on knee and shoulder surgery. The knowledge of the trends and incidences of these procedures help to validate and discuss the results of clinical studies and registers.