Why Is There a Range in Time Returning to Preoperative Activity Habits After Femoroacetabular Impingement Treatment in Recreational Athletes?

CONTEXT: Professional athletes showed excellent results after hip preserving procedures. However, there is still a lack of knowledge regarding the rate of return to activity and the rehabilitation time of recreational athletes. Thus, the aim of this study was to investigate factors that were associated with an extended return-to-activity time in nonprofessional athletes. DESIGN: Retrospective, quantitative case-control study. METHODS: This study included 47 cases (45 nonprofessional athletes), which were divided according to return-to-activity time (short term: 0.0-7.0 mo vs long term: >7.0 mo). The clinical outcome were evaluated with the modified Harris hip score, the nonarthritic hip score, the Western Ontario and McMaster Universities Osteoarthritis Index, and the University of California, Los Angeles activity score. For statistical analysis between both groups, an unpaired student t test and a paired Wilcoxon test were used. In addition, the sports behavior, intraoperative findings, and surgical procedures were also assessed. RESULTS: After a mean follow-up of 4.3 years (±0.6; 3.4-5.6), the overall postoperative modified Harris hip score was 81.8 points, the nonarthritic hip score was 75.8 points, the Western Ontario and McMaster Universities Osteoarthritis Index was 36.7 points, and the University of California, Los Angeles activity score was 7.9. Compared with the preoperative results, all scores improved significantly (P < .001). Patients of the short-term return-to-activity group showed a higher preoperative activity diversity and, postoperatively, a higher rate in high-impact sports (P = .024). CONCLUSIONS: After mini-open arthrotomy for femoroacetabular impingement syndrome treatment, 92.5% of the recreational athletes returned to sports activity. The findings did not detect factors influencing the return-to-activity time. However, a higher preoperative diversity of activities and a shift to high-level impact sport activities might support a shorter rehabilitation.

The lateral joint space width is essential for the outcome after arthroscopically assisted mini-open arthrotomy for treatment of a femoroacetabular impingement: an analysis of prognostic factors for the success of this hip-preserving technique.

PURPOSE: The purpose of this study was to analyze predicting factors for a conversion to a total hip replacement (THR) after mini-open arthrotomy for treatment of femoroacetabular impingement (FAI). METHODS: Between 2011 and 2016, we identified 32 patients, who were treated for FAI with a mini-open arthrotomy and received after mean time of 2.1 ± 1.4 years a THR. These patients were compared to 47 cases who did not receive a THR (mean follow-up: 4.3 ± 0.7 years) to explore pre- and intra-operative factors associated with a conversion to THR. The results were presented in separated Kaplan-Meier curves with log rank test for significance and hazard ratios. RESULTS: A lateral joint space width of > 4 mm showed a higher THR-free survival rate compared to < 4 mm (p = 0.001); analogously one-sided (acetabular/femoral) 3-4° cartilage damage had a comparable THR-free survival rate than 1-2° kissing lesions (p = 0.001). Furthermore, an intact labrum without treatment and good cartilage status, a refixed labrum after rim resection in case of a pincer type FAI, or a refixed teared labrum were associated with a longer THR-free time than an untreated labrum accompanied by a poor cartilage status or an ossified labrum (p = 0.002). The strongest independent factor for a conversion to THR was femoral cartilage damage grade 1 and higher (p = 0.046). However, the rate of available patients was 53.0%. CONCLUSION: The success of a joint-preserving mini-open arthrotomy seems to be dependent on the status of the radiological joint space width and the intra-operative cartilage status of the lateral edge.

[Epidemiology, prevention and early detection of femoroacetabular impingement syndrome (FAIS)]. / Epidemiologie, Prävention und Früherkennung des Femoroazetabulären Impingement-Syndroms (FAIS).

During the last two decades femoroacetabular impingement syndrome (FAIS) has gained importance and is one of the main causes of hip pain in young adults. FAIS is a motion-related clinical pathology of the hip that represents symptomatic contact between the proximal femur and the acetabulum. Symptoms, clinical signs, and imaging findings must be present to diagnose FAIS. Especially the development of the cam-FAIS seems to be associated with an overuse of the growth plate during adolescence. Here an approach may be found for the prevention of the development of FAIS. Sufficient evidence through high-quality long-term results is yet lacking.

The outcome of the partial resurfacing arthroplasty of the hip shows high numbers of failures and conversion to total arthroplasty.

PURPOSE: Local cartilage and bony defects, which are too large for joint preserving cartilage treatment are difficult to treat. The implantation of a mini-resurfacing implant (Hemicap®, 2med, Hamburg, Germany) may be a possible alternative treatment for these patients. This partial replacement fills the defect and restores a smooth and continuous articular surface. The aim of this study was to determine short- to midterm results of the treatment of local cartilage defects of the femoral head using the Hemicap®. METHODS: Since 04/2011 16 patients with osteonecrosis of the femoral head greater ARCO stage II or local femoral cartilage lesions (< 35 mm) were treated with the implantation of the Hemicap® implant. A clinical and radiological follow-up was conducted. RESULTS: The clinical results showed a significant improvement of the function and pain of the hip according to the Harris Hip Score from 56 (±14) preoperative to 77 (±15) post-operative 25 months after implantation of the Hemicap®. In the meantime, in four patients the Hemicap® had to be converted to a total hip arthroplasty due to loosening, progredience of the osteonecrosis or degeneration of the acetabulum. CONCLUSIONS: The implantation of the mini-resurfacing implant Hemicap® seemed to be an alternative treatment for local cartilage defects of the femoral head to postpone the implantation of a total hip arthroplasty. However, the clinical outcome seems to be inferior to total hip arthroplasty. Furthermore, due to a high rate of conversion to total hip arthroplasty (25%) the application of this implant is questionable. If the implant is considered as a treatment option at least patient selection and enlightenment for this treatment with the high risk of failure and progression of osteoarthritis is very important.

Biomechanical characteristics of bioabsorbable magnesium-based (MgYREZr-alloy) interference screws with different threads.

PURPOSE: Degradable magnesium implants have received increasing interest in recent years. In anterior cruciate ligament reconstruction surgery, the well-known osteoconductive effects of biodegradable magnesium alloys may be useful. The aim of this study was to examine whether interference screws made of MgYREZr have comparable biomechanical properties to commonly used biodegradable screws and whether a different thread on the magnesium screw has an influence on the fixation strength. METHODS: Five magnesium (MgYREZr-alloy) screws were tested per group. Three different groups with variable thread designs (Designs 1, 2, and 3) were produced and compared with the commercially available bioabsorbable Bioacryl rapid polylactic-co-glycolic acid screw Milagro®. In vitro testing was performed in synthetic bone using artificial ligament fixed by an interference screw. The constructs were pretensioned with a constant load of 60 N for 30 s followed by 500 cycles between 60 N and 250 N at 1 Hz. Construct displacements between the 1st and 20th and the 21st and 500th cycles were recorded. After a 30 s break, a maximum load to failure test was performed at 1 mm/s measuring the maximum pull-out force. RESULTS: The maximum loads to failure of all three types of magnesium interference screws (Design 1: 1,092 ± 133.7 N; Design 2: 1,014 ± 103.3 N; Design 3: 1,001 ± 124 N) were significantly larger than that of the bioabsorbable Milagro® interference screw (786.8 ± 62.5 N) (p < 0.05). However, the greatest maximum load was found with magnesium screw Design 1. Except for a significant difference between Designs 1 and 2, there were no further significant differences among the four groups in displacement after the 20th cycle. CONCLUSIONS: Biomechanical testing showed higher pull-out forces for magnesium compared with a commercial polymer screw. Hence, they suggest better stability and are a potential alternative. The thread geometry does not significantly influence the stability provided by the magnesium implants. This study shows the first promising results of a degradable material, which may be a clinical alternative in the future.

Repair of retropatellar cartilage defects in the knee with microfracture and a cell-free polymer-based implant.

INTRODUCTION: To analyze magnetic resonance imaging (MRI) at 3T and the clinical outcome in a short-term pilot study after treatment of retropatellar cartilage defects with microfracturing and subsequent covering with the cell-free chondrotissue(®) polyglycolic acid-hyaluronan implant. METHODS: Five consecutive patients after microfracturing and defect coverage with the chondrotissue(®) implant immersed with autologous serum were included. After a mean follow-up of 21 months (range 11-31 months), defect fill and repair tissue quality was assessed by 3-T MRI followed by applying established MRI scoring systems. The patients' situation was assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS) and a patients' satisfaction questionnaire. RESULTS: Magnetic resonance imaging showed good to excellent defect fill with complete integration. The mean MOCART score was 61 (range 50-75) points. The mean Henderson score was 7 (range 6-9) points. All patients showed subchondral bone alterations. The KOOS showed good values in all sub-categories in 4 out of 5 patients and a mean overall score of 73 (range 40-90) points. Two patients rated the outcome as excellent, two as good and one as fair. All patients would have the procedure again and recommend it. CONCLUSIONS: In this small case series, the coverage of symptomatic retropatellar cartilage defects with the chondrotissue(®) implant after microfracturing was safe and feasible with improvement of the patients' situation at short-term follow-up. LEVEL OF EVIDENCE: IV, case series.

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

PURPOSE: To compare clinical and radiological outcomes of static and dynamic medial patellofemoral ligament (MPFL) reconstruction techniques. METHODS: In 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. RESULTS: No 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. CONCLUSIONS: Both techniques provided satisfactory short-term outcomes. LEVEL OF EVIDENCE: III.

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

PURPOSE: The 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. METHODS: A 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. RESULTS: Elongation 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. CONCLUSIONS: Our 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).

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.

Biomechanical comparison of different fixation techniques for reconstruction of tibial avulsion fractures of the anterior cruciate ligament.

PURPOSE: The most common fixation techniques for tibial avulsion fractures of the anterior cruciate ligament (ACL) described in the literature are screw and suture fixation. The fixation of these fractures with the TightRope® device might be an alternative. Up to now it has been commonly used in other injuries, such as acromioclavicular joint or syndesmosis ruptures. The purpose of this study was to evaluate the biomechanical properties of different fixation techniques for the reconstruction of tibial avulsion fractures. METHODS: Type III tibial avulsion fractures were simulated in 40 porcine knees. Each specimen was randomly assigned to one of four groups: (1) anterograde screw fixation, (2) suture fixation, (3) TightRope® fixation or (4) control group. The initial displacement, strength to failure and the failure mode were documented. RESULTS: The maximum load to failure was 1,345 ± 155.5 N for the control group, 402.5 ± 117.6 N for the TightRope® group, 367 ± 115.8 N for the suture group and 311.7 ± 120.3 N for the screw group. The maximum load to failure of the control group was significantly larger compared to all other groups. The initial dislocation was 0.28 ± 0.09 mm for the control group, 0.55 ± 0.26 mm for the TightRope® group, 0.84 ± 0.15 mm for the screw group and 1.14 ± 0.9 mm for the suture group. The initial dislocation was significantly larger for the suture group compared to the TightRope® and control groups. CONCLUSIONS: The TightRope® fixation shows significantly lower initial displacement compared to the suture group. The TightRope® fixation might be an alternative for the repair of ACL tibial avulsion fractures that can be used arthroscopically.

Anti-Inflammatory Effect of Vitamin C during the Postoperative Period in Patients Subjected to Total Knee Arthroplasty: A Randomized Controlled Trial.

Vitamin C, a potent reducing and antioxidant agent, plays an important role in the body, aiding in the growth of cartilage and bones. It is also involved in mechanisms that help reduce inflammation and its effects on the body. In addition, vitamin C decreases pro-inflammatory cytokines, such as IL-6, which produce acute-phase proteins such as CRP and influence inflammatory markers such as ESR. We carried out a study with 110 patients who underwent total knee replacement surgery. We divided the patients into two groups, in which the intervention group received 15 g of parenteral vitamin C during the immediate postoperative period while the control group did not. Patients who received 15 g of vitamin C after total knee replacement surgery had decreased inflammatory markers, specifically CRP and ESR. Overall, administering vitamin C in the post-surgical period results in improved management of inflammation, as evidenced by a decrease in CRP and ESR values. This leads to faster recovery and better healing outcomes for patients undergoing total knee replacement surgery. Furthermore, the beneficial effects of vitamin C in reducing proinflammatory cytokines, reducing the need for opioid analgesics, and its mild adverse effects make it a promising adjuvant in managing postoperative recovery.

Empfehlungen der AG Klinische Geweberegeneration zur Behandlung von Knorpelschäden am Kniegelenk. / Empfehlungen der AG Klinische Geweberegeneration zur Behandlung von Knorpelschäden am Kniegelenk.

The Working Group of the German Orthopedic and Trauma Society (DGOU) on Tissue Regeneration has published recommendations on the indication of different surgical approaches for treatment of full-thickness cartilage defects in the knee joint in 2004, 2013 and 2016. Based upon new scientific knowledge and new developments, this recommendation is an update based upon the best clinical evidence available. In addition to prospective randomised controlled clinical trials, this also includes studies with a lower level of evidence. In the absence of evidence, the decision is based on a consensus process within the members of the working group.The principle of making decision dependent on defect size has not been changed in the new recommendation either. The indication for arthroscopic microfracturing has been reduced up to a defect size of 2 cm2 maximum, while autologous chondrocyte implantation is the method of choice for larger cartilage defects. Additionally, matrix-augmented bone marrow stimulation (mBMS) has been included in the recommendation for defects ranging from 1 to 4.5 cm2. For the treatment of smaller osteochondral defects, in addition to osteochondral transplantation (OCT), mBMS is also recommended. For larger defects, matrix-augmented autologous chondrocyte implantation (mACI/mACT) in combination with augmentation of the subchondral bone is recommended.

Accessibility of extra-articular pathologies of iliopsoas tendon and bursitis of greater trochanter in hip arthroscopy.

PURPOSE: Different pathologies leading to psoas tendon pain and chronic bursitis of the greater trochanter are well known. The purpose of the study was to underline the accessibility of the psoas tendon at lesser trochanter, reproduce the results and measure the distances to anatomical landmarks. METHODS: Twelve hips of six human cadavers underwent hip arthroscopy. The accessibility of the iliopsoas tendon at the lesser trochanter and the bursa at the greater trochanter was documented with the camera. In addition to the usual access portals, alternative ventral ports were analysed concerning accessibility of the lesser trochanter. Afterwards, arthroscopy needles were placed along the extra-articular portals followed by dissection. The distances of the portals in relation to important anatomical landmarks were analysed. RESULTS: The accessibility to the iliopsoas tendon at the lesser trochanter and to the bursa at the greater trochanter throughout the conventional portals was reproducible. Sufficient distances to the important anatomical landmarks could be shown. The mean distance of the distal ventro-lateral and the wide distal ventro-lateral portal to the nervous cutaneous femoris lateralis was 26.8 ± 5.4 mm and 32.2 ± 3.9 mm. The mean distance from the more ventral located portals to the nervous arteria and vena femoralis was 28.3 ± 2.1 mm. CONCLUSION: This is the first study known to us that describes in detail the accessibility of the extra-articular structures underlined by anatomical preparation. In addition, it was demonstrated that a more ventrally located portal had sufficient distance to the important neurovascular structures of the ventral femur and can also be used in addendum if necessary.

Cementless short stem hip arthroplasty METHA® as an encouraging option in adults with osteonecrosis of the femoral head.

INTRODUCTION: The implantation of a total hip arthroplasty is the standard treatment for patients with progressive osteonecrosis. However, there is uncertainty about the type of arthroplasty that provides the best outcome and whether short stem arthroplasty represents a reasonable alternative for young patients in order to have more options in case of revision. This uncertainty exists due to the lack of studies analysing contemporary short stem arthroplasty in osteonecrosis. AIM: The aim of this study was to determine the outcome of the METHA(®) short stem arthroplasty in patients with progressive osteonecrosis. PATIENTS AND METHODS: This study evaluated the clinical and radiological short- to midterm results after implantation of the cementless short stem arthroplasty METHA(®). 73 hips in 64 patients with progessive osteonecrosis after implantation of the METHA(®) arthroplasty were investigated by measuring the clinical outcome, the Harris Hip Score (HHS) and visual analogue pain scale for the preoperative stage and follow-up. Radiological analyses of X-rays were conducted to assess the bone ingrowth as well as subsidence, osteolysis or fracture. RESULTS: The pain scale improved from preoperatively 7.8 to postoperatively 1.7, while the HHS increased from 41.4 to 90.6 points 34 months post-surgery. Complications associated with revision of the METHA(®) short stem included two traumatic femoral shaft fracture and one deep infection. The radiological assessment showed good bone ingrowth in all patients despite osteonecrosis. CONCLUSION: The study confirms encouraging results as well as good bone ingrowth of the cementless short stem arthroplasty METHA(®) even in patients with osteonecrosis.

[Management of FAIS in professional soccer athletes and return to sports]. / Management der FAIS-Sportlerhüfte im Profifußball und "return to sports".

The prevalence of femoroacetabular impingement syndrome in professional soccer athletes is high. Professional training and treatment conditions ensure an effective conservative therapy focusing on dynamic stability, motion control, muscle balance and core stability. In the case of persistent limitations, indication for surgery has to be considered carefully. The probability is high that return to a professional level of soccer is feasible. However, the period of rehabilitation is long, leading to a potential conflict area between economic and medical interests. Good communication and intensive patient education are essential.

[Persistent or recurrent symptoms after surgery for femoroacetabular impingement syndrome (FAIS) : Pathology, diagnostics and therapy]. / Persistierende oder wiederkehrende Beschwerden nach femoroazetabulärer Impingement-Chirurgie : Ursachen, Diagnostik und Therapie.

BACKGROUND: Femoroacetabular impingement syndrome (FAIS) has gained vast importance in the last two decades. Multiple studies have shown that if untreated, early osteoarthritis of the hip joint may result. Hip arthroscopy is one of the fastest growing procedures in the orthopedic cosmos, having already replaced the majority of (mini) open techniques in FAIS surgery. However, with the recent remarkable increase in the volume of hip arthroscopies performed worldwide, the number of patients with persistent or recurrent symptoms after FAIS surgery is also growing. PATHOLOGY: Potential underlying pathologies are misresection of the bony deformity, insufficiency fracture of the femoral head neck junction or the femoral subchondral head itself (SIFFH), adhesions, failed chondrolabral or capsular treatment, septic arthritis, heterotopic ossification or a wrong indication in the case of osteoarthritis that is already too advanced. Most of these occur more often during the extensive learning curve for hip arthroscopy. DIAGNOSTICS: High-quality imaging plays a key role in determining the need for revision surgery vs. further conservative treatment. Therapeutical avenues are shown with the common goal of proper detection and correction of the underlying pathology to address unsatisfactory FAIS treatment outcomes and ensure long-term survival of the native hip joint.

Impact of continuous passive motion on rehabilitation following total knee arthroplasty.

BACKGROUND AND PURPOSE: There is an ongoing controversy in respect of the usage of continuous passive motion (CPM) following total knee arthroplasty (TKA). We analysed the impact of CPM on the early rehabilitation after TKA and the clinical outcome over the time. METHODS: Forty patients were prospectively randomized to postoperative protocols following TKA. Half of them (n = 20) received the standard manual therapy alone and the others (n = 20) were treated additionally with CPM. Identical implants were used in all patients. Passive range of movement (PROM) was noted. Patient satisfaction and knee function was evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) as well as the Knee Society Score (KSS) at time of discharge and 2 years postoperatively. RESULTS: The patients in the solitary manual therapy group (MT) showed preoperatively a 7.2° greater PROM (p = .03) with 5.4° higher flexion (p = .05). Analogously, the KSS presented with 42.7 points a higher score result compared to the CPM group with 35.9 points (p = .03). Although the preoperative ability with 105.2° for flexion and 97.2° for the PROM were in favour of the group without CPM (99.8° resp. 90.0°), at time of discharge the patients with CPM reached with 111.0° a significant higher flexion and with 109.0° a higher PROM (MT group: 107.0° resp. 103.5°) (p = .04/.02). At 2 years follow-up both scores (WOMAC/KSS) and function (extension, flexion and PROM) were balanced (p > .05). Patella resurfacing showed no impact on the clinical results at discharge or at time of last follow-up (p > .05). DISCUSSION: Although the addition of CPM did significantly improve knee flexion in the early postoperative stage, the difference might not represent a clinical relevance. Further, there were no notable effects on long-term clinical and functional results following TKA, so the routine application of CPM in the above stated setting might be ceased.

Proceeding from direct lateral to anterolateral approach in total hip arthroplasty: A closer look on radiological and clinical aspects.

INTRODUCTION: Since less invasive approaches for total hip arthroplasty (THA) are promoted, our aim was to compare direct lateral (DLA) and anterolateral approach (ALA) under otherwise identical conditions. METHODS: Pre - and postoperative x-rays from 200 propensity matched patients (DLA vs. ALA) were evaluated for anatomical reconstruction. RESULTS: Overall, the cup position was within the safe zone in both group while the mean center of rotation (COR) was placed more medial and cranial in both groups compared to preoperative anatomy (p > 0.05). The mean leg elongation was comparable between both approaches (p > 0.05). Postoperatively the WOMAC improved about 90%. CONCLUSION: This study confirmed that the ALA can be safely used for THA in minimal invasive setting.

Biomechanical Properties of a Novel Biodegradable Magnesium-Based Interference Screw.

Magnesium-based interference screws may be an alternative in anterior/posterior cruciate ligament reconstruction. The well-known osteoconductive effects of biodegradable magnesium alloys may be useful. It was the purpose of this study to evaluate the biomechanical properties of a magnesium based interference screw and compare it to a standard implant. A MgYREZr-alloy interference screw and a standard implant (Milagro®; De Puy Mitek, Raynham, MA, USA) were used for graft fixation. Specimens were placed into a tensile loading fixation of a servohydraulic testing machine. Biomechanical analysis included pretensioning of the constructs at 20 N for 1 min following cyclic pretensioning of 20 cycles between 20 and 60 N. Biomechanical elongation was evaluated with cyclic loading of 1000 cycles between 50 and 200 N at 0.5 Hz. Maximum load to failure was 511.3±66.5 N for the Milagro® screw and 529.0±63.3 N for magnesium-based screw (ns, P=0.57). Elongations after preload, during cyclical loading and during failure load were not different between the groups (ns, P>0.05). Stiffness was 121.1±13.8 N/mm for the magnesium-based screw and 144.1±18.4 for the Milagro® screw (ns, P=0.32). MgYREZr alloy interference screws show comparable results in biomechanical testing to standard implants and may be an alternative for anterior cruciate reconstruction in the future.