Marco Ezechieli

Bone marrow stromal cells in a liquid fibrin matrix improve the healing process of patellar tendon window defects.

Following injury, ligaments and tendons do not regain their normal biological and biomechanical status. This study analyzed whether an injection of human bone marrow stromal cells (BMSC) or human fibroblast in a liquid fibrin matrix influences the histological results, ultrastructural morphology, mRNA expression of essential extracellular matrix proteins, and material properties of the healing tissue. Standardized full-thickness, full-length defects of the central portion of patellar tendons were created in 96 immunodeficient rats, and filled with human BMSC in a fibrin matrix (BMSC group), human fibroblasts in a fibrin matrix (fibroblast group), or fibrin matrix only (matrix group), or left untreated (defect group). Histological sections revealed more mature tissue formation with more regular patterns of cell distribution in the BMSC group, without signs of ectopic tissue formation into bone or cartilage. Mean collagen fibril diameter and relative area covered by collagen fibrils were significantly higher at 10 and 20 days postoperatively in the BMSC group compared to the defect and matrix groups, and comparable to normal tendon tissue. Further, collagen I mRNA expression, collagen I/collagen III mRNA ratio, and Youngs modulus were significantly increased at 20 days postoperatively in comparison to the defect and matrix groups. In the fibroblast group, only mean collagen fibril diameter was significantly higher compared to the defect group, whereas the other biological and biomechanical parameters were not significantly improved. This study reveals that an injection of BMSC in a liquid fibrin matrix stimulates histological, ultrastructural, molecular biologic, and biomechanical parameters of patellar tendon healing, whereas injection of fibroblasts in fibrin matrix had only minor effects on the stimulation of tendon healing.

Dynamic versus static reconstruction of the medial patellofemoral ligament for recurrent lateral patellar dislocation

PurposeTo compare clinical and radiological outcomes of static and dynamic medial patellofemoral ligament (MPFL) reconstruction techniques.MethodsIn a retrospective, matched-paired, cohort analysis, 30 patients surgically treated for recurrent lateral patellar dislocation were divided into two groups of 15 patients matched for inclusion and exclusion criteria. The static technique group underwent rigid fixation of the gracilis tendon at the anatomic femoral MPFL insertion and the superomedial border of the patella; the dynamic technique group underwent detachment of the gracilis tendon at the pes anserinus with fixation to the proximal medial patellar margin via tunnel transfer obliquely through the patella. Kujala, Lysholm, and Tegner scores; pain level; and pre- and postoperative radiographic changes of patellar height, patellar tilt, and bisect offset were compared.ResultsNo significant between-group differences were found in mean Kujala, Tegner, Lysholm, or visual analogue scale scores or radiographic parameters. One case of resubluxation was observed in the dynamic group. All but one patient in each group would have been willing to undergo the procedure again.ConclusionsBoth techniques provided satisfactory short-term outcomes.Level of evidenceIII.

Access to the Hip Joint From Standard Arthroscopic Portals: A Cadaveric Study

PURPOSE Our purpose was to study and describe the areas of the hip joint that can be safely visualized and operated on using a variety of portals for the central and peripheral compartments. METHODS Twelve hip joints in 6 human cadavers were examined through 9 different central and peripheral arthroscopic portals. Markings of the accessible areas within the joint were made through an arthroscope. Dissection of the cadavers was carried out for final evaluation of the visible areas and those accessible for instruments. During dissection, anatomic proximity of the portals to relevant neurovascular structures was measured. RESULTS The central compartment was sufficiently accessible using the anterior, anterolateral, and posterolateral portals, with slight limitations in the posteromedial corner. A more medial portal did not offer substantial advantages regarding accessibility but decreased the safety distance to the femoral nerve. With regard to the peripheral compartment, the combination of the anterolateral and posterolateral portals allowed visualization of most of the joint. It was observed that the structure at highest risk of injury for the central anterior and the peripheral anterolateral portals was the lateral femoral cutaneous nerve. CONCLUSIONS In hip arthroscopy, the use of the standard anterior, anterolateral, and posterolateral portals allows proper accessibility of the central compartment, with slight limitations in the posteromedial corner. A more medial portal is not recommended with regard to its risk-benefit ratio. The peripheral compartment of the hip joint is sufficiently visible using the anterolateral and posterolateral portals. For treatment of specific pathologic conditions, a variation of these portals improves surgical accessibility. The anatomic structure at highest risk of injury during hip arthroscopy is the lateral femoral cutaneous nerve. CLINICAL RELEVANCE The general objectives of this study were to prepare surgeons to develop appropriate concepts of surgery and to facilitate preoperative planning.

Examination of a biodegradable magnesium screw for the reconstruction of the anterior cruciate ligament: A pilot in vivo study in rabbits

The reconstruction of the anterior cruciate ligament is, for the most part, currently performed with interference screws made of titanium or degradable polymers. The aim of this study was to investigate the use of biodegradable magnesium interference screws for such a procedure because of their known biocompatibility and reported osteoconductive effects. The left tibiae of each of 18 rabbits were implanted with a magnesium-based (MgYREZr-alloy) screw, and another 18 with a titanium-based control. Each group was divided into observation periods of 4, 12 and 24weeks. After sacrifice, μCT scans were acquired to assess the amount of the gas liberated and the degradation rate of the implant. Histological evaluations were performed to investigate the local tissue response adjacent to the implant and to assess the status of the attachment between the tendon and the bone tissue. The μCT scans showed that liberation of gas was most prominent 4weeks after implantation and was significantly decreased by 24weeks. All screws remained in situ and formed a sufficient connection with the tendon and sufficient osseous integration at 24weeks. Histological evaluations showed neither inflammatory reactions nor necrosis of the tendon. The results of this pilot study in rabbits indicate that this magnesium-based interference screw should be considered as an alternative to conventional implant materials.

Muscle strength of the lumbar spine in different sports

BACKGROUND The ability to stabilize the body center (core stability) against dynamic movements of the extremities and capability to absorb repetitive loading forces in the trunk play a crucial role in any professional sport specific performance. OBJECTIVE The aim our cross sectional level of evidence 3 study was to determine, if athletes of different sport disciplines showed specific trunk strength profiles and if these were different from a control group. METHODS 20 ironman triathletes, 18 amateur volleyball and 18 amateur soccer players were tested for their individual isometric strength of the lumbar spine in three planes of motion using a standartized test device. RESULTS The test profile revealed similar strength parameters for extension and lateral flexion to the left in each of the 3 study groups tested. The lateral flexion to the right was significantly stronger than in the control group (soccer > volleyball > triathlon). In all 3 groups, weaknesses were found in the abdominal musculature, showing highly significant differences in flexion and bilateral rotation compared to the control group (p=0.001). CONCLUSIONS Our study shows that sports specific training for triathlon, as well as the team sports soccer and volleyball, does not lead to balanced trunk musculature and core stability. In consequence predisposing injury and muscle dysbalane can trigger pain syndromes.

The influence of a single-radius-design on the knee stability

Prostheses with single radius (SR) design were supposed to be as good as the physiological kinematic and stability of the knee. This in-vitro biomechanical study compared SR to a multiple radius (MR) design on the one hand and seven left human knee specimens were used. The SR and MR knee prosthesis where implanted with a navigation system. We measured varus/valgus deviation of the mechanical axis and the deviation of the joint-line to the epicondyle-line in different knee flexion degrees (0°, 30°, 45°, 60° and 90°) with and without 15 Nm of varus and valgus stress. Without varus/valgus-stress in all three groups (physiological knee, SR and MR prosthesis) the results were located on the varus-site. The variation of the SR was less than the MR, without being significant. Under varus and valgus stress varus/valgus axis deviation constantly grew. From 0-60° no significant deviation between the two prosthesis models was found. At 90° flexion varus/valgus deviation with the SR component was significantly (p ⩽ 0.05) smaller compared to the MR design. This in-vitro study showed that the SR prosthesis is significantly more stable in the coronal plane than the MR in higher flexion degrees. This could have an improved effect on biomechanical stability with a higher clinical function after SR-TKA.

Biodegradation of a magnesium alloy implant in the intercondylar femoral notch showed an appropriate response to the synovial membrane in a rabbit model in vivo

Degradable magnesium alloys are promising biomaterials for orthopedic applications. The aim of this study was to evaluate the potential effects on both the synovial membrane (synovialis) and the synovial fluid (synovia) of the degradation products of a MgYREZr-pin implanted in the intercondylar femoral notch in a rabbit model. Thirty-six animals were randomized into two groups (MgYREZr or Ti6Al4V alloy) of 18 animals each. Each group was then divided into three subgroups with implantation periods of 1, 4, and 12 weeks, with six animals in each subgroup. The initial inflammatory reaction caused by the surgical trauma declined after 12 weeks of implantation, and elucidated a progressive recovery of the synovial membrane. Compared with control Ti6Al4V pins, there were no significant differences between the groups. However, after 12 weeks, recovery of the synovial membrane was more advanced in the titanium group, in which 92% showed no signs of synovitis, than in the magnesium group. A cytotoxicity test with L929 cells and human osteoblasts (HOB) was also conducted, according to EN ISO 10993-5/12, and no toxic leachable products were observed after 24 h of incubation. In conclusion, the MgYREZr alloy seems to be a suitable material for intra-articular degradable implants.

CCD and offset after Nanos short stem in total hip arthroplasty

BACKGROUND Many short stems for total hip arthroplasty have been introduced by the manufacturers only during the last decade. One of them is the Nanos short stem (Smith and Nephew, Marl, Germany). The development of short stems was aimed at preserving bone and soft tissue by utilizing a minimally invasive approach, thus allowing a quick return to an active life. It was purpose of this study to evaluate the radiological changes after using this device. METHODS We present the radiological results of 202 cementless THAs which were performed in 172 patients using the Nanos stem. Radiological evaluation was performed using standing anterior-posterior (AP) and lateral radiographs of the proximal femur preoperatively, postoperatively and during the follow up. We analyzed the preoperative and postoperativ CCD angle, the subsisdence, preoperative and postoperative offset, osteolysis, bone resorption, increased density, neocortex and periarthricular ossifications. RESULTS One stem had to be revised due to subsidence four days after implantation. Two cups (BiconPlus, Smith and Nephew, Marl, Germany) had to be revised during the time of follow up due to an aseptic cup loosening. Two stems showed radiolucent lines at the implant-bone-interface at the last follow-up. An increase of bone density could be detected in 18 hips (8.9%). 14 hips showed periarticular ossifications. Measurable subsidence was detected in a total of four stems (1.9%). The preoperative neck-shaft-angle angle was 133.8 ± 4.4° (range: 118.5-146.2) and the neck-shaft-angle angle at the time of follow up was 134.6 ± 4.3° (range: 123.3-147; P< 0.05). The preoperative and postoperative offset changed from 109.3 ± 11.9 mm (range: 80.9-131.6) to 109.7 ± 12.3 mm (range: 79.7-155.6; P< 0.05). CONCLUSION In summary, this study shows that a correct anatomical reconstruction is possible with a device of this design. The outcome is comparable to that of other short stems. Further studies should be performed in a prospective and randomized design to evaluate the advantage of such a device with a higher level of evidence.

Sports Activity After Treatment of Residual Hip Dysplasia With Triple Pelvic Osteotomy Using the Tönnis and Kalchschmidt Technique

Background: Pelvic osteotomies are performed to prevent the progression of osteoarthritis and its associated pain due to adult hip dysplasia, particularly for young patients with no or low-grade osteoarthritis. No data are available concerning levels of sporting activity before and after triple pelvic osteotomy (TPO). Therefore, the aim of this study was to provide comprehensive data on levels of sporting activity and the subjective outcome of patients after this complex operation. Hypothesis: Patients can return to a higher level of sports activity after TPO compared with their preoperative level. Study Design: Case series; Level of evidence, 4. Methods: Between 2003 and 2011, a total of 116 triple pelvic osteotomies were performed at a single institution; the Tönnis and Kalchschmidt technique was used on 91 patients. After exclusion criteria for this study were applied, 77 patients remained (59 females and 18 males); the mean ± SD age at operation was 26 ± 3.9 years. To study outcomes, patients were asked to complete both the Harris hip score (HHS) and the Hip disability and Osteoarthritis Outcome Score (HOOS) preoperatively and at postoperative follow-up. Their level of activity was determined according to the University of California, Los Angeles (UCLA) activity score. Patients rated their hip movement and overall satisfaction preoperatively and at postoperative follow-up using a visual analog scale for sporting activity, physical fitness level, and level of pain experienced while performing their sport. Results: The mean ± SD follow-up time was 6.2 ± 1.4 years. The mean HHS changed significantly from 63.3 ± 15.6 preoperatively to 90.1 ± 10.8 at follow-up (P < .001), and the mean HOOS changed significantly from 52.9 ± 20.1 to 82 ± 17.1 at follow-up (P < .001). The mean UCLA activity score changed significantly from 4.8 ± 2.1 to 7.7 ± 1.4 at follow-up (P < .001). Conclusion: Patients achieved a higher level of sports activity postoperatively. The postoperative level of participation in sports was superior, with a shift from low- to high-impact activities.

The biomechanics of biodegradable versus titanium interference screw fixation for anterior cruciate ligament augmentation and reconstruction

PurposeThe ligament augmentation and reconstruction system (LARS) is one of the options available for anterior cruciate ligament (ACL) reconstruction. To date, however, there are no published data regarding the biomechanical properties of LARS fixation for ACL reconstruction. The aim of this study was to investigate the biomechanical properties of various LARS interference-screw fixations.MethodsA total of 100 LARS ligaments were fixed in porcine femurs with five different interference screws (four biodegradable screws and one titanium interference screw) introduced from inside-out or extra-articularly outside-in. Each group consisted of ten specimens. The constructs were cyclically stretched and subsequently loaded until failure. We evaluated the maximum load before failure, elongation during cyclic loading, stiffness, and failure mode.ResultsElongation during cyclical loading for all devices tested was significantly larger between the first and 20th cycles than between the 20th and 500th cycles (p < 0.05). Maximum failure load was not significantly lower for the biodegradable screws than for the titanium screws (p > 0.05). All specimens failed because of ligament pull-out from the bony tunnel.ConclusionsOur findings suggest that biomechanical secure fixation of the LARS for ACL reconstruction can be achieved using either biodegradable or titanium interference screws. The stability of fixation is independent of the approach, type of investigation, and type of fixation (extra-articular outside-in or intra-articular inside-out).