Biomechanical comparison of a multidirectional locking plate and conventional plates for the osteosynthesis of mandibular angle fractures-A preliminary study.

PURPOSE: The objective of surgical fracture management is to reduce and fixate fractures accurately and rapidly. Two osteosynthesis plates are usually used in the treatment of mandibular angle fractures to enhance torsional stiffness. We conducted biomechanical tests under static and cyclic loading to assess whether a single locking plate is as efficacious as two conventional plates in the osteosynthesis of mandibular angle fractures. MATERIALS AND METHODS: Fracture gaps were created in synthetic mandible replicas. After pretests, the stiffness of a single locking plate and different types of non-locking, two-plate systems was assessed and compared under static and cyclic loading. The plates were subjected to a maximum static load of 750 N and underwent cyclic loading at a constant force of 400 N during a maximum of 500,000 cycles. RESULTS: No plastic deformation occurred in the static tests. Both types of osteosynthesis showed high static stability. The locking plate was significantly stiffer than the non-locking plates (p = 0.0079). Cyclic loading tests did not reveal any significant differences. CONCLUSION: Within the limitations of this preliminary study, a single locking miniplate appears to be as efficacious in biomechanical tests as non-locking, two-plate systems for the management of mandibular angle fractures.

Complications during removal of conventional versus locked compression plates: is there a difference?

BACKGROUND: Osteosynthesis plate removal is one of the most commonly performed procedures in orthopaedic surgery. Due to technological advances and the quality of increasing osteosynthesis material, more and more locked plates have been implanted over the last 20 years. The aim of this study was to determine whether the complication rate during plate removal differs between conventional and locked plates. MATERIAL AND METHODS: In this retrospective cohort study, 620 patients were included and divided into two groups based on the type of plate (locked and conventional). Technical complications during implant removal included screw breakage, destroyed screw head, implant breakage, remaining implant material, refracture, bony or soft tissue overgrowth. The following plate-associated complications were identified: osteosynthesis plate not detachable, plate bent or broken, necessity of special tools or plate loosened. Three types of screw-related complications were observed: screw not detachable, screw broken or screw dislocated. RESULTS: Overall, complications related to the plate or screws were documented in 110 of the 620 cases. These complications occurred in 48 of the 382 cases involving conventional osteosynthesis (7.7% of all removals, 12.6% of all conventional removals) and in 62 of the 238 cases involving locked plate osteosynthesis (10.0% of all removals, 26.1% of all locked plate removals). The statistical analysis showed a significantly higher implant-related complication rate with locked plates compared to the conventional plates (p < 0.01). CONCLUSIONS: Hardware removal can be a complication-afflicted operation, especially cases involving locked-plate removal should only be performed if a strong indication is evident. Possible benefits of the procedure should be considered carefully, taking the cost-benefit ratio into account.

Biomechanical evaluation of novel ultrasound-activated bioresorbable pins for the treatment of osteochondral fractures compared to established methods.

BACKGROUND: Osteochondral injuries often lead to osteoarthritis of the affected joint. All established systems for refixation of osteochondral defects show certain disadvantages. To address the problem of reduced stability in resorbable implants, ultrasound-activated pins were developed. By ultrasound-activated melting of the tip of these implants, a more secure anchoring is assumed. MATERIALS AND METHODS: The aim of the study was to investigate if ultrasound-activated pins can provide secure fixation of osteochondral fragments compared to screws and conventional resorbable pins. In a biomechanical laboratory setting, osteochondral fragments of the medial femoral condyle of sheep were refixated with ultrasound-activated pins [US fused poly(L-lactide-co-D,L-lactide) (PLDLLA) pins], polydioxanone (PDA) pins and conventional titanium screws. Anchoring forces of the different fixation methods were examined, registered and compared concerning shear force and tensile force. RESULTS: Concerning the pull out test, the US fused PLDLLA pins and titanium screws (~122 N and ~203 N) showed comparable good results, while the PDA pins showed significantly lower anchoring forces (~18 N). Examination of shear forces showed a significantly higher anchoring of the screws (~248 N) than the US fused PLDLLA pins (~218 N). Nevertheless, the US fused PLDLLA pins could significantly outperform the PDA pins (~68 N) concerning shear forces. CONCLUSION: The US fused PLDLLA pins demonstrated a comparable anchorage to the fixation with screws, but were free from the disadvantages of metal implants, i.e. the need for implant removal. The PDA pin application showed inferior biomechanical properties.

Matrix-Associated Autologous Chondrocyte Implantation: A Clinical Follow-Up at 15 Years.

INTRODUCTION: A prospective clinical investigation was carried out in order to clarify whether Matrix-associated autologous chondrocyte implantation (MACI) results in clinical improvement at long-term follow-up. HYPOTHESIS: MACI will result in clinical improvement at long-term follow-up. STUDY DESIGN: Case series; level of evidence, 4. METHODS: Thirty-eight patients were treated with MACI. These patients were evaluated for up to a mean of 16 years (range 15-17 years) after the intervention. Three different scores (Lysholm-Gilquist score, International Cartilage Repair Society score, and Tegner score) formed the basis of this study. Overall, we were able to obtain valid preoperative and postoperative results from 18 (47%) of 38 patients. In 1 patient, both knees were treated. In 4 patients, an arthroplasty was implanted over the course of time; thus they were excluded from this case series. In conclusion, follow-up of 15 knees was performed in the recent series. RESULTS: In subjective rating, 12 out of 14 patients (86%) rated the function of their knee as much better or better than before the index procedure. All numerical outcome scores showed significant improvement compared to the preoperative value (preoperative/postoperative at 5 years/postoperative at 15 years): Lysholm score 59.6 (±24.6)/78.6 (±21.5)/82.7 (±11.3), International Knee Documentation Committee score 50.6 (±22.7)/64.7 (±21.6)/69.7 (±18.7), Tegner score 3.0 (±2.2)/3.6 (±1.5)/5.2 (±1.7). CONCLUSION: The significantly improved results on 3 scores after 15 years suggest that MACI represents a suitable treatment of local cartilage defects in the knee.

Osteosynthesis-screw augmentation by ultrasound-activated biopolymer--an ovine in vivo study assessing biocompatibility and bone-to-implant contact.

OBJECTIVES: Screw fixation and fragment anchoring in osteoporotic bones is often difficult. Problems like the cut out phenomenon and implant migration in osteoporotic bones have been reported. One possibility of improving the anchoring force of screws is augmentation of the screw. Cement-augmented screws in spinal surgery could exhibit a better anchoring in osteoporotic bones. METHODS: The purpose of this study was to examine the effect of screw augmentation using a resorbable polymer. Ultrasound-activated biodegradable pins were used for the purpose of a resorbable augmentation technique. Cannulated screws were inserted into the femur of 12 sheep and augmented by an ultrasound-activated polylactic acid (PLDLA) pin. In a paired approach, four screws were implanted in each animal: 2× a 10-mm thread and 2× a 20-mm thread, both of which were augmented with polymer. Both screws, named A and B, were also applied without augmentation (control group) and implanted into the contralateral hind limb. After 4, 8, and 12 weeks, the sheep were euthanized and a macroscopical and histological examination followed. RESULTS: The polymer spread well out of the screws into the cancellous lacunae. Around the polymer, the peripheral bone showed signs of healthy and active bone tissue. No evidence of inflammation or infection was observed. The boneto-implant contact was significantly higher in the augmented screws. Biocompatibility was proven in histopathological examination. After 12 weeks, no pathological changes were found. CONCLUSION: Ultrasound-activated polymer augmentation of cannulated screws may improve the anchoring in osteoporotic bone. ARTICLE FOCUS: Can screw augmentation using a resorbable polymer improve the bone-to-implant contact in case of screw osteosynthesis? Is there any effect on the surrounding tissue by the induced temperature and liquefied polymer? Can biocompatibility be proven by this new osteosynthesis? KEY MESSAGES: Screw augmentation by ultrasound-activated biopolymer leads to a significant higher bone-to-implant contact than pure screw osteosynthesis. No tissue damage could be observed by the application of the SonicFusion™. STRENGTH AND LIMITATIONS OF THIS STUDY: The ovine in vivo study concept can simulate physiological conditions. First examination of screw augmentation by ultrasound-activated biopolymer. No biomechanical testing of the higher bone-to-implant contact by now.

Arthroscopic-assisted hook plate fixation for acromioclavicular joint dislocation.

PURPOSE: We present a new technique of arthroscopic-assisted AC-hook plate fixation for acromioclavicular joint dislocation with all the advantages of minimally invasive surgery and the possibility to treat concomitant pathologies. METHODS: Initially a glenohumeral arthroscopy is performed to address concomitant intra-articular injuries. Under subacromial visualisation the drill hole for the hook of the plate can be exactly positioned in the acromion. The hook plate is put in place under visual control. RESULTS: The initial results (n = 3) are promising with good to excellent results in the Constant score [90.5 (range 82-100)] in all cases studied. The cross-body test was slightly positive in one case. The median follow-up time after the index procedure was seven months (range five to ten). CONCLUSIONS: In conclusion, arthroscopic-assisted reconstruction of acromioclavicular joint separation is feasible and may provide patients with all the benefits of AC-hook fixation with decreased risks related to open surgery. The described technique is recommended for all surgeons familiar with arthroscopic surgery.

Evidence Based Development of a Novel Lateral Fibula Plate (VariAx Fibula) Using a Real CT Bone Data Based Optimization Process During Device Development.

Development of novel implants in orthopaedic trauma surgery is based on limited datasets of cadaver trials or artificial bone models. A method has been developed whereby implants can be constructed in an evidence based method founded on a large anatomic database consisting of more than 2.000 datasets of bones extracted from CT scans. The aim of this study was the development and clinical application of an anatomically pre-contoured plate for the treatment of distal fibular fractures based on the anatomical database.48 Caucasian and Asian bone models (left and right) from the database were used for the preliminary optimization process and validation of the fibula plate. The implant was constructed to fit bilaterally in a lateral position of the fibula. Then a biomechanical comparison of the designed implant to the current gold standard in the treatment of distal fibular fractures (locking 1/3 tubular plate) was conducted. Finally, a clinical surveillance study to evaluate the grade of implant fit achieved was performed. The results showed that with a virtual anatomic database it was possible to design a fibula plate with an optimized fit for a large proportion of the population. Biomechanical testing showed the novel fibula plate to be superior to 1/3 tubular plates in 4-point bending tests. The clinical application showed a very high degree of primary implant fit. Only in a small minority of cases further intra-operative implant bending was necessary. Therefore, the goal to develop an implant for the treatment of distal fibular fractures based on the evidence of a large anatomical database could be attained. Biomechanical testing showed good results regarding the stability and the clinical application confirmed the high grade of anatomical fit.

Biomechanical analysis of a synthetic femoral spiral fracture model: Do end caps improve retrograde flexible intramedullary nail fixation?

BACKGROUND: Elastic Stable intramedullary Nailing (ESIN) of dislocated diaphyseal femur fractures has become an accepted method for the treatment in children and adolescents with open physis. Studies focused on complications of this technique showed problems regarding stability, usually in complex fracture types such as spiral fractures and in older children weighing > 40 kg. Biomechanical in vitro testing was performed to evaluate the stability of simulated spiral femoral fractures after retrograde flexible titanium intramedullary nail fixation with and without End caps. METHODS: Eight synthetic adolescent-size femoral bone models (Sawbones® with a medullar canal of 10 mm and a spiral fracture of 100 mm length identically sawn by the manufacturer) were used for each group. Both groups underwent retrograde fixation with two 3.5 mm Titanium C-shaped nails inserted from medial and lateral entry portals. In the End Cap group the ends of the nails of the eight specimens were covered with End Caps (Synthes Company, Oberdorf, Switzerland) at the distal entry. RESULTS: Beside posterior-anterior stress (4.11 Nm/mm vs. 1.78 Nm/mm, p < 0.001), the use of End Caps demonstrated no higher stability in 4-point bending compared to the group without End Caps (anterior-posterior bending 0.27 Nm/mm vs. 0.77 Nm/mm, p < 0.001; medial-lateral bending 0.8 Nm/mm vs. 1.10 Nm/mm, p < 0.01; lateral-medial bending 0.53 Nm/mm vs. 0.86 Nm/mm, p < 0.001) as well as during internal rotation (0.11 Nm/° vs. 0.14 Nm/°, p < 0.05). During compression in 9°- position and external rotation there was no statistical significant difference (0.37 Nm/° vs. 0.32 Nm/°, p = 0.13 and 1.29 mm vs. 2.18 mm, p = 0.20, respectively) compared to the "classic" 2-C-shaped osteosynthesis without End Caps. CONCLUSION: In this biomechanical study the use of End Caps did not improve the stability of the intramedullary flexible nail osteosynthesis.

Mid-term results after operative treatment of rockwood grade III-V acromioclavicular joint dislocations with an AC-hook-plate.

Acromioclavicular joint dislocations often occur in athletic, young patients after blunt force to the shoulder. Several static and dynamic operative procedures with or without primary ligament replacement have been described. Between February 2003 and March 2009 we treated 313 patients suffering from Rockwood III-V lesions of the AC joint with an AC-hook plate. 225 (72 %) of these patients could be followed up. Mean operation time was 42 minutes in the conventional group and 47 minutes in the minimal invasive group. The postoperative pain on a scale from 1 to 10 (VAS-scale) was rated 2.7 in the conventional group and 2.2 in the minimal invasive group. Taft score showed very good and good results in 189 patients (84%). Constant score showed an average of 92.4 of 100 possible points with 89 % excellent and good results and 11 % satisfying results. All patients had some degree of pain or discomfort with the hook-plate in place. These symptoms were relieved after removal of the plate. The overall complication rate was 10.6 %. There were 6 superficial soft tissue infections, 1 fracture of the acromion, 7 redislocations after removal of the hook-plate. We observed 4 broken hooks which could be removed at the time of plate removal, 4 seromas and 2 cases of lateral clavicle bone infection, which required early removal of the plate. We can conclude that clavicle hook plate is a convenient device for the surgical treatment of Rockwood Grade III-V dislocations, giving good mid-term results with a low overall complication rate compared to the literature. Early functional therapy is possible and can avoid limitations in postoperative shoulder function.

Treatment of posttraumatic sternal non-union with a locked sternum-osteosynthesis plate (TiFix).

Only a minority of sternal fractures require osteosynthesis. Unstable non-union of the sternum is a very disabling condition which often requires treatment. The method most often used is tension-wiring. Due to loosening of the tensile strength or wire cut-out, this method often fails. We report the results of locked plate osteosynthesis of sternal non-union and displaced fractures. Over a five-year period, 12 patients have been treated using this method in a multicentre trial. Mean age at trauma was 32.8 years, the implant used in all cases was an 8-hole titanium plate, the fixation of the screws is based on the principles of angular stable fixation.In all cases the index procedure was possible, in all cases there was bony healing at follow-up examination.Multidirectional locked plating offers a reliable method for the successful treatment of sternal nonunion and displaced fractures.

Posttraumatic severe infection of the ankle joint - long term results of the treatment with resection arthrodesis in 133 cases.

Although there is a clear trend toward internal fixation for ankle arthrodesis, there is general consensus that external fixation is required for cases of posttraumatic infection. We retrospectively evaluated the technique and clinical long term results of external fixation in a triangular frame for cases of posttraumatic infection of the ankle. From 1993 to 2006 a consecutive series of 155 patients with an infection of the ankle was included in our study. 133 cases of the advanced "Gächter" stage III and IV were treated with arthrodesis. We treated the patients with a two step treatment plan. After radical debridement and sequestrectomy the malleoli and the joint surfaces were resected. An AO fixator was applied with two Steinmann-nails inserted in the tibia and in the calcaneus and the gap was temporary filled with gentamicin beads as the first step. In the second step we performed an autologous bone graft after a period of four weeks. The case notes were evaluated regarding trauma history, medical complaints, further injuries and illnesses, walking and pain status and occupational issues. Mean age at the index procedure was 49.7 years (18-82), 104 patients were male (67.1%). Follow up examination after mean 4.5 years included a standardised questionnaire and a clinical examination including the criteria of the AOFAS-Score and radiographs. 92.7% of the cases lead to a stable arthrodesis. In 5 patients the arthrodesis was found partly-stable. In six patients (4,5%) the infection was not controllable during the treatment process. These patients had to be treated with a below knee amputation. The mean AOFAS score at follow up was 63.7 (53-92). Overall there is a high degree of remaining disability. The complication rate and the reduced patient comfort reserve this method mainly for infection. Joint salvage is possible in the majority of cases with an earlier stage I and II infection.

Treatment of Distal Lower Leg Fractures: Results with Fixed-Angle Plate Osteosynthesis.

Twenty-five patients with closed distal tibial fractures were treated with a fixed-angle (locked) plate osteosynthesis. The study period was from 1.1.06 to 31.12.07. According to AO classification, there were three A1, eight A2, nine A3, one B2, two C1, and two C3 fractures. All patients had a follow up examination after an average of 16.6 months. Complications included a technical mistake (fixation in slight malangulation), two infections, and one non union that showed consolidation after 15 months. All other patients reached bone consolidation and full weight bearing after an average of 3.5 months. The ankle range of motion for all patients was, on average, flexion/extension 18°/35°, without restrictions on the walking distance. No loss of reduction occurred. Fixed-angle plate osteosynthesis is a good alternative to intramedullary nailing when treating closed distal lower leg fractures. It is a demanding surgical method with good clinical and functional results.

Operative Treatment and Soft Tissue Management of Open Distal Tibial Fractures - Pitfalls and Results.

Open tibial fractures usually result from high-energy trauma. Severe soft-tissue injuries are often combined with open fractures of the distal tibia. A consecutive series of 42 patients with open extraarticular distal tibial fractures (Gustilo I-IIIc) operated on between July 2006 and February 2009 were included in the study reported here. We performed open reduction and internal fixation for the Gustilo I cases. Soft tissue was closed directly after antibiotic beads had been temporarily applied. For the Gustilo II and III cases, our treatment protocol included soft-tissue debridement of all devitalized soft tissue and bone fragments, pulsatile jet irrigation, and external stabilization. Soft tissue was temporarily closed with Epigard_ after the application of antibiotic beads. A second-look operation was scheduled after 3-5 days. Gustilo II patients needed an average of 1.1 (0-3) revisions until wound closure, compared to the average of 2.1 revisions necessary for the Gustilo III patients. It took 5.6 (0-16) days to obtain definitive wound closure in the Gustilo II patients and 9.9 (3-28) days in the Gustilo III patients. Skin grafting was sufficient for definitive softtissue closure in ten cases, local flaps in eight cases, and free musculocutaneous flaps were needed in six cases. Gustilo II patients with primary wound closure remained hospitalized for 11 days, while patients with secondary wound closure stayed in hospital for an average of 20 days. Our early results concerning infection rate, number of reoperations, and time to bony consolidation can be compared with other studies. Functional results will have to be evaluated at clinical follow-up.

Deltoid muscular flap transfer for the treatment of irreparable rotator cuff tears.

The purpose of this study was to evaluate the outcome of deltoid muscle flap transfer for the treatment of irreparable rotator cuff tears. In a retrospective study 20 consecutive patients were evaluated. The index procedure took place between 2000 and 2003. Fifteen patients were male, mean age was 62 years. Inclusion criterion was a rotator cuff defect Bateman grade IV. Exclusion criteria were smaller defects, shoulder instability and fractures of the injured shoulder. An open reconstruction with acromioplasty and a pedicled delta flap was performed. Follow up period was mean 42 months. Follow-up included clinical examination, Magnetic Resonance Imaging (MRI) and the Constant and Simple (CS) shoulder tests. According to the Constant shoulder test the results were good in 13 patients, fair in 5 and unsatisfactory in 2. The pre-operative Constant Score improved from mean 25.7 points (±5.3) to 72.3 (±7.8) at follow-up. The mean values for the subcategories of CS increased significantly from 3.9 to 14.4 points for pain and from 4.2 to 15.9 points for activities daily routine (p<0.05). The change in range of motion and strength were not significant (p>0.05). Results of the Simple Shoulder Test showed a significant increase of the mean values from pre-operative 4.3 to 14.7 points post-operatively. MRI showed a subacromial covering of the defect in all cases, all flaps where intact on MRI but always the flap showed marked fatty degeneration. In conclusion, the delta flap is a simple method for the repair of large defects of the rotator cuff leading to satisfying medium results.

Results of total hip replacement using the Robodoc surgical assistant system: clinical outcome and evaluation of complications for 97 procedures.

BACKGROUND: A computerized robotic surgical system was developed from 1986 by the Thomas J. Watson Research Center. In 1992 the system unit Orthodoc and the milling robot Robodoc were first used on humans. We present the results achieved with Robodoc-assisted total hip arthroplasty in 97 hips. METHODS: Between 1997 and 2002, 143 total hip replacements (128 patients) were performed using the Robodoc system. This is a consecutive series. Complete follow-up was possible in 97 hips at a mean follow-up period of 3.8 years. RESULTS: Technical complications directly related to the robotic device occurred in nine cases (9.3%). The pre-operative Merle d'Aubigne score was determined at 8.1 points compared to a post-operative mean score of 16.2. There was no sign of femoral stem loosening on radiographs. CONCLUSIONS: Robotic-assisted total hip arthroplasty with the Orthodoc/ Robodoc system achieves equal results as compared to a manual technique. However, there was a high number of technical complications directly or indirectly related to the robot.