Minimally invasive and open surgical treatment of proximal tibia fractures using a polyaxial locking plate system: a prospective multi-centre study.

PURPOSE: The purpose of this study was to determine whether a polyaxial locking plate of the latest generation (NCB PT(®), Zimmer Inc.) which can be applied both open and minimally invasively, can be used as a routine method of treatment for proximal tibia fractures. METHODS: Eighty-six patients (35 women, 51 men; mean age 51 years) were enrolled in this prospective multicentre trial. Ninety-six percent of the fractures were intra-articular (AO type B and C); 36 % were treated open and 64 % minimally invasively. Follow-up was obtained three, six and 12 months after surgery. RESULTS: No implant failure occurred. At 12 months, the functional result using a knee-specific score was good to excellent in 95 %, and 99 % of the fractures were radiologically healed. CONCLUSION: The system is a versatile implant for proximal tibia fracture treatment. Polyaxiality and a specific locking mechanism are compatible with different fracture patterns. The minimally invasive technique effectively protects soft tissues but should not be performed at the expense of fracture reduction. Early functional results and complication rate are comparable to those in the literature.

Influence of fracture type and surgeon experience on the emission of radiation in distal radius fractures.

INTRODUCTION: Ionising radiation is a potential risk for potentially exposed personnel. Only a few studies have examined the factors contributing to the emission of radiation in orthopaedic trauma procedures. We hypothesize that the experience of the surgeon and the fracture type influence the emission of radiation intraoperatively. METHODS: In a retrospective analysis, we examined 100 consecutive distal radius fractures receiving a volar plate osteosynthesis. The following parameters were documented: demographic data, plate system, fracture type, duration of the surgical procedure and duration of the emission of radiation, the experience level of the surgeon and the first assisting surgeon. RESULTS: Of all included patients (74 female), 48 had a type A, 7 a type B and 45 a type C fracture. The duration of radiation was longer for type C fractures [1.04 min (min)] in comparison to type A fractures (0.88 min) (P = 0.8152). In the type C subgroup, the highest amount of radiation was required for type C3 fractures (1.6 min), which was significantly more in comparison to type A (P = 0.0460) and type C1 fractures (P = 0.0089). The intraoperative emission of radiation (P = 0.00141) and the procedure time (P = 0.0006) depended on the experience of the surgical team. CONCLUSION: The emission of radiation during this procedure depends on the fracture type and the experience of the surgical team. Operating theatre personnel should be aware of the higher emission rates during the treatment of type C fractures and in teaching hospitals with inexperienced team members.

Biomechanical in vitro assessment of fixed angle plating using a new concept of locking for the treatment of osteoporotic proximal humerus fractures.

Locked plating attempts to improve mechanical stability via better anchorage of the screws in the bone. In 22 paired osteoporotic humeri an AO/ASIF 11-B 1 fracture was created. Locked and conventional plating using the same device of the latest generation was performed. Torsional loading around three axes (x = varus/valgus, y = flexion/extension, z = axial rotation) with an increasing moment (2, 3.5, 5 and 7.5 N·m) was applied. Interfragmentary motion within the locked group was lower for all three axes with higher cumulative survival rates (p < 0.05). The typical mode of failure was loss of fixation in the humeral head occurring earlier in the conventional group. The locking mechanism investigated provides more ultimate strength in an osteoporotic proximal humerus fracture model. Correlation with BMD suggests that this device may especially be suitable for use in osteoporotic bone.

Second generation locked plating of proximal humerus fractures--a prospective multicentre observational study.

Surgical treatment of most displaced proximal humerus fractures is challenging due to osteoporosis. Locking plates are intended to provide superior mechanical stability. In a prospective multicentre study 131 patients were treated with second generation locked plating (NCB-PH, Zimmer, Inc.). The open procedure (n = 78) was performed using a deltopectoral approach; the minimally invasive technique (n = 53) involved percutaneous reduction and an anterolateral deltoid split approach. Clinical and radiological follow-up was obtained. Improvement in function (ROM) was statistically significant. Fracture type (AO) had the most significant impact on the incidence of complications. The most frequent complications detected were intra-articular screw perforation (15%) and secondary displacement (8%). Complication rate and functional outcome of the NCB-PH are comparable to reports in the literature. Not all problems are likely to be solved by this new generation of implants, i.e. secondary dislocation still occurred in 8% of our patients.

Minimally invasive application of the non-contact-bridging (NCB) plate to the proximal humerus: an anatomical study.

OBJECTIVES: To describe a minimal anterolateral acromial approach for minimally invasive (MI) treatment of fractures of the proximal humerus (PH) with the Non-Contact-Bridging (NCB) plate. DESIGN: 1) Cadaver study and 2) clinical case series. SETTING: 1) University Institute of Anatomy and the 2) University Level I trauma center. SPECIMENS/PATIENTS: 1) Ten fresh frozen human humeri and 2) 22 patients with 22 isolated proximal humeral fractures. INTERVENTION: 1) Minimal anterolateral acromial approach with MI application of the NCB-PH plate followed by dissection of the axillary nerve and 2) MI fracture fixation using this approach and technique of plate insertion. MAIN OUTCOME MEASURES: 1) Integrity of the axillary nerve and evaluation of its relationship to the implant, and 2) early postoperative functional results. RESULTS: In the cadaver study, the nerve directly crossed over the percutaneously inserted plate in all the arms. The nerve then divided into two branches anterior to the plate in eight arms and divided into two branches directly over the plate in two arms. One branch of the axillary nerve in one arm was injured. In the clinical case series, no intraoperative complications relating to the approach or the implant occurred. No symptoms of axillary nerve lesion have been detected so far in the early follow-up. CONCLUSIONS: The minimal anterolateral acromial approach is suitable for MI technique to apply the NCB-PH. The relationship of the axillary nerve to the plate is anatomically close. We recommend that strict bone contact be maintained during plate insertion and that screw insertion complies with the guidelines provided for this technique. In a small clinical cases series, the plate and screws were inserted in accordance with these guidelines and no axillary nerve lesions have yet been detected.

Head Injury in Children: Has a Change in Circumstances Caused an Increase in Treatment Numbers?

The number of hospitalizations for head injuries in children is rising. The exact causes remain unclear. We analyzed data of children aged between 0 and 18 years who sustained a head injury between 2010 and 2011. The analysis focused on data related to demographics, trauma mechanism, clinical course, results of imaging scans, concomitant injuries, and outcome. A total of 794 inpatient cases of head injury were treated. The leading mechanism of injury was a fall (at home) primarily at the age of 1 to 4 years (46.5%), with the majority of the children sustaining a mild brain injury (764, 96.2%). Neurosurgery was performed in 21 (2.64%) cases; average hospital stay was 2.9 days (range: 0-68 days). This study is not able to confirm that children are increasingly being brought to the hospital by their parents because of new trauma mechanisms or parents' uncertainty, nor can we confirm that the number of nonaccidental injuries is rising.

The PFNA® Augmented in Revision Surgery of Proximal Femur Fractures.

OBJECTIVES: Modern implants for proximal femur fracture treatment have clearly improved clinical results. However, complications, including cut-out and loss of reduction, requiring revision surgery still occur. A major challenge in these cases is a loss of bone stock due to the existing implant, which is usually exacerbated by osteoporosis. A potential solution is the augmentation of implants, for example, of the femoral neck blade using bone cement. MATERIALS AND METHODS: Ten patients (five loosening of femoral neck implant, two pseudarthrosis, two implant failures and one acute fracture) were included. The initial hardware was removed and a PFNA augmented was implanted. The perforated femoral neck blade was augmented using polymethyl methacrylate cement. Clinical and radiological follow-up was performed at a mean of 5.4 months (SD ±4.34). The main outcome parameters were fracture healing and implant-related complications. RESULTS: Technical handling was uneventful in all cases. No cement leakage into the joint occurred in any of the cases. The mean amount of cement injected was 5.3 ml. The fracture healed during follow-up in all cases except two patients who died from causes unrelated to the procedure and prior to complete consolidation. Problem-free elective hardware removal of the PFNA augmented was performed in two cases. DISCUSSION: The PFNA augmented is a potential implant for joint-preserving revision surgery in proximal femur fractures. The augmentation improves implant anchorage in the impaired bone stock. In this preliminary series, no negative biological side effects of the cement (i.e. osteonecrosis) were observed.

Delayed bone healing following high tibial osteotomy related to increased implant stiffness in locked plating.

INTRODUCTION: Asymmetrical callus formation and incomplete bone formation underneath stiff locking plates have been reported recently in clinical and experimental fracture healing studies. After similar effects were observed in the outcome of high tibial osteotomy (HTO) patients, a retrospective study was performed to quantify the frequency and level of such incomplete healing cases. MATERIAL AND METHODS: Twenty-three patients treated with medial open wedge HTO and locking plate (Tomofix™) for posttraumatic or congenital genu varum were investigated. No bone grafts were applied to fill the osteotomy gap. The median correction angle was 8° (5-18°). Elective hardware removal was performed after a median of 19.5 months (12-58 months) following an uneventful clinical course. The most recent postoperative X-ray available (median 21 months; 13-56 months) was evaluated for consolidation of the osteotomy. We performed an in vitro biomechanical experiment using the same HTO on a loaded cadaver knee joint to compare interfragmentary movements (IFMs) when using regular locking screws with the Tomofix™ plate and screws that enabled dynamic stabilisation of this plate. RESULTS: Fifteen patients (65%) displayed incomplete consolidation of the osteotomy underneath the locking plate (10.9% of the osteotomy length) and cortical deficiency. The time to implant removal for these patients of 27 months was longer than the 21 months for the patients with a complete osteotomy gap healing. The biomechanical experiment demonstrated that very low IFMs and corresponding interfragmentary strain occur underneath the plate when using regular locking screws. Replacement with dynamic screws resulted in an increased IFM. DISCUSSION AND CONCLUSIONS: These results support the hypothesis that low bone formation underneath locking plates is induced by increased stiffness. This high stiffness situation could be altered by replacing the standard screws with dynamic screws which allow for a movement of 0.35mm perpendicular to the screw axis. This resulted in an approximately threefold increase in the IFM and may be a potential concept to avoid incomplete bone healing under stiff plate fixations.

Mechanical quantification of local bone quality in the humeral head: a feasibility study.

OBJECTIVES: Surgical treatment of proximal humerus fractures can be challenging due to osteoporosis. The weak bone stock makes stable implant anchorage difficult, which can result in low primary stability. Accordingly, significant failure rates, even with modern locking plates, are reported in the literature. Intraoperative knowledge of local bone quality could be helpful in improving results. This study evaluates the feasibility of local bone quality quantification using breakaway torque measurements. MATERIALS AND METHODS: A torque measurement tool (DensiProbe™) was developed to determine local resistance to breakaway offered by the cancellous bone in the humeral head to quantify local bone quality. The tool was adapted to a standard locking plate (PHILOS, Synthes), allowing measurement in the positions of the six humeral head screws, as provided by the aiming device of the plate. Two hundred and seventy measurements were performed in 44 fresh cadaveric human humeri. RESULTS: Handling of the tool was straight forward and provided reproducible results for the six different positions. The method allows discrimination between the respective positions with statistical significance, and thus provides reliable information on the local distribution of bone quality within the humeral head. DISCUSSION: This study introduces a new method using breakaway torque to determine local bone quality within the humeral head in real time. Because DensiProbe is adapted to a standard locking plate, there is the potential for intraoperative application. The information provided could enable the surgeon to improve fixation of osteoporotic proximal humerus fractures.

Biomechanical in vitro assessment of screw augmentation in locked plating of proximal humerus fractures.

INTRODUCTION: Proximal humerus fracture fixation can be difficult because of osteoporosis making it difficult to achieve stable implant anchorage in the weak bone stock even when using locking plates. This may cause implant failure requiring revision surgery. Cement augmentation has, in principle, been shown to improve stability. The aim of this study was to investigate whether augmentation of particular screws of a locking plate aimed at a region of low bone quality is effective in improving stability in a proximal humerus fracture model. MATERIALS AND METHODS: Twelve paired human humerus specimens were included. Quantitative computed tomography was performed to determine bone mineral density (BMD). Local bone quality in the direction of the six proximal screws of a standard locking plate (PHILOS, Synthes) was assessed using mechanical means (DensiProbe™). A three-part fracture model with a metaphyseal defect was simulated and fixed with the plate. Within each pair of humeri the two screws aimed at the region of the lowest bone quality according to the DensiProbe™ were augmented in a randomised manner. For augmentation, 0.5 ml of bone cement was injected in a screw with multiple outlets at its tip under fluoroscopic control. A cyclic varus-bending test with increasing upper load magnitude was performed until failure of the screw-bone fixation. RESULTS: The augmented group withstood significantly more load cycles. The correlation of BMD with load cycles until failure and BMD with paired difference in load cycles to failure showed that augmentation could compensate for a low BMD. DISCUSSION AND CONCLUSION: The results demonstrate that augmentation of screws in locked plating in a proximal humerus fracture model is effective in improving primary stability in a cyclic varus-bending test. The augmentation of two particular screws aimed at a region of low bone quality within the humeral head was almost as effective as four screws with twice the amount of bone cement. Screw augmentation combined with a knowledge of the local bone quality could be more effective in enhancing the primary stability of a proximal humerus locking plate because the effect of augmentation can be exploited more effectively limiting it to the degree required.

Mechanical assessment of local bone quality to predict failure of locked plating in a proximal humerus fracture model.

The importance of osteoporosis in proximal humerus fractures is well recognized. However, the local distribution of bone quality in the humeral head may also have a significant effect because it remains unclear in what quality of bone screws of standard implants purchase. The goal of this study was to investigate whether the failure of proximal humerus locked plating can be predicted by the DensiProbe (ARI, Davos, Switzerland). A 2-part fracture with metaphyseal impaction was simulated in 12 fresh-frozen human cadaveric humeri. Using the DensiProbe, local bone quality was determined in the humeral head in the course of 6 proximal screws of a standard locking plate (Philos; Synthes GmbH, Solothurn, Switzerland). Cyclic mechanical testing with increasing axial loading until failure was performed. Bone mineral density (BMD) significantly correlated with cycles until failure. Head migration significantly increased between 1000 and 2000 loading cycles and significantly correlated with BMD after 3000 cycles. DensiProbe peak torque in all screw positions and their respective mean torque correlated significantly with the BMD values. In 3 positions, the peak torque significantly correlated with cycles to failure; here BMD significantly influenced mechanical stability. The validity of the DensiProbe was proven by the correlation between its peak torque measurements and BMD. The correlation between the peak torque and cycles to failure revealed the potential of the DensiProbe to predict the failure of locked plating in vitro. This method provides information about local bone quality, potentially making it suitable for intraoperative use by allowing the surgeon to take measures to improve stability.

Where do locking screws purchase in the humeral head?

INTRODUCTION: One of the limiting factors in finding the best osteosynthesis approach in proximal humerus fractures is the current lack of information on the properties of the cancellous bone regions engaged by the implants fixing the epiphysis. The aim of this study is to assess the densitometric and mechanical characteristics of these regions when using a proximal humerus locking plate (PHLP). MATERIALS AND METHODS: Nineteen PHLPs were mounted on cadaveric humeri using only their three most distal screws. Subsequently, the plates were removed and the bones were scanned using high-resolution peripheral quantitative computed tomography. Bone mineral density (BMD) was determined in the intact proximal epiphysis and in the exact locations where the six proximal screws would have been positioned concluding the instrumentation. Each plate was then repositioned on its bone and a minimally destructive local torque measurement was performed in the same six locations. A statistical analysis was performed to detect significant differences in the investigated parameters between screw positions, and to test the ability of local torque values to discriminate the bone mineral density of the entire humeral head (BMD(TOT)). RESULTS: Novel data about the cancellous bone engaged by the screws of a PHLP are provided. Different epiphyseal locations showed statistically significant different properties. A local torque measurement was a good predictor of the BMD(TOT). CONCLUSION: Position and direction of the epiphyseal screws on a locking implant are determinant to engage bone regions with significantly better bone quality. A breakaway torque measurement in a given screw position can distinguish between humeral heads with different densitometric properties.

Electrophysiological assessment of the deltoid muscle after minimally invasive treatment of proximal humerus fractures - a clinical observation.

The minimal anterolateral acromial approach offers a less invasive access to the proximal humerus. Functional impairment following this procedure may be caused by paresis of the deltoid muscle as a result of iatrogenic injury to the axillary nerve. It was addressed whether electromyography (EMG) of the deltoid muscle gives evidence for an axillary nerve lesion in association with the minimal anterolateral acromial approach.Twenty-three patients (14 men, 9 women; average age 58 years) with proximal humerus fractures were included in this clinical observation. Follow-up was performed 6 weeks (6w), 6 months (6m) and 12 months (12m) postoperatively. EMG changes indicating either lesion of the axillary nerve or direct muscle trauma were distinguished in "acute", "chronic" and "combined" and semi quantified in "slight", "moderate" and "severe". Patients were examined clinically (standard neurological examination and Constant Score).Three cases of incomplete axillary nerve lesion with limited functional impairment were detected. Subclinical EMG signs of neural impairment of the deltoid muscle were observed frequently (6w, N = 8; 6m, N = 8; 12m, N = 7). Functional outcome did not show an association with EMG.Most patients presented with subclinical and most likely trauma- related neurogenic lesions of the deltoid muscle following the anterolateral acromial approach. Despite the fact that the axillary nerve does not function normally following this less-invasive approach for fixation of proximal humerus fractures, this does not appear to affect the clinical outcome. Prospective studies with larger sample sizes are required to determine the effect of axillary nerve retraction in the more commonly used deltopectoral approach.

Clinical results for minimally invasive locked plating of proximal humerus fractures.

OBJECTIVES: To describe the minimally invasive treatment of fractures of the proximal humerus using the Non-Contact-Bridging (NCB) plate. The system allows secondary locking of screws to the plate with a locking cap and polyaxial (30 degrees radius) screw placement. DESIGN: Prospective cohort study. SETTING: University Level I trauma center. PATIENTS: Fifty-four patients with unstable fractures of the proximal humerus. INTERVENTION: Minimal anterolateral acromial approach to the proximal humerus, percutaneous fracture reduction, and minimally invasive application of the NCB plate. MAIN OUTCOME MEASUREMENTS: Constant Score and radiologic follow-up (anteroposterior and transscapular). Visual Analog Scale for subjective evaluation of pain and function. RESULTS: After 17 months, the average Constant Score was 66.8 points (87% of the age- and sex-related normal values). Implant-related complications (plate impingement, screw perforation into the glenohumeral joint, loosening of screws) occurred in nine cases (17%). The rate of avascular necrosis was low (5.5%) and no cases of nonunion were seen. CONCLUSIONS: The effectiveness of the NCB is similar to other published methods of treatment for fractures of the proximal humerus and potentially provides a less invasive option for this problem. Complication rates and functional outcome in this series are comparable to the literature. An important factor in this technique is the process of percutaneous fracture reduction. The NCB plate is suitable for both a minimally invasive technique or standard open reduction and internal fixation through a deltopectoral approach; the surgeon must decide which approach is best for each particular fracture pattern and should be comfortable with both techniques.

CT-guided interventions in orthopedics.

PURPOSE: In this study we present our experience with CT-guided interventions for musculoskeletal diseases. Technical details, advantages and disadvantages and the accuracy of the method are described. MATERIALS AND METHODS: Between 2002 and 2005 we performed 77 CT-guided interventions on 72 patients (42 men, mean age 43.9 +/- 24.4 years, and 30 women, mean age 54.2 +/- 20.3) with (suspected) fracture, tumor or infection. RESULTS: Forty-one tumors, metastases or bone cysts, 17 infections, 12 bone alterations (e.g. osteoporosis, fracture) and 4 joints were diagnosed or treated. In three patients a tumor or an infection could be excluded. The duration of the procedure was 29.1 +/- 16.8 min. We did not see any intraoperative complication. However, the intervention had to be repeated in two patients, as the collected specimen was insufficient for histopathological evaluation in one patient, and in the other the nidus of osteoid osteoma persisted. The effective accuracy was 90.5%. Two patients were diagnosed first and then treated by screw osteosynthesis or corticoid steroid infiltration. One patient with an osteoid osteoma of the tibia fell and sustained a fracture of the tibial shaft. CONCLUSION: CT-guidance can substantially support diagnostic and therapeutic procedures in bone and soft tissues, especially if located in deep areas of the body, which are difficult to reach using open approaches.

BMP-2, BMP-4, and PDGF-bb stimulate chemotactic migration of primary human mesenchymal progenitor cells.

For bone development, remodeling, and repair; the recruitment of mesenchymal progenitor cells (MPC) and their differentiation to osteoblasts is mandatory. The process of migration is believed to be regulated in part by growth factors stored within the bone matrix and released by bone resorption. In this study, primary human MPCs and to osteoblasts differentiated progenitor cells were examined for chemotaxis in response to human basic fibroblast growth factor (rhbFGF), human transforming growth factor beta 1 (rhTGF-beta1), human platelet derived growth factor bb (rhPDGF-bb), human bone morphogenetic protein-2 (rhBMP-2), and recombinant bone morphogenetic protein-4 of Xenopus laevis (rxBMP-4) from 0.001 to 1.0 ng/ml each. The results of migration were expressed as a chemotactic index (CI). Migration of primary human progenitor cells was stimulated by rhBMP-2, rxBMP-4, and rhPDGF-bb in a dose-dependent manner. The increase of CI was up to 3.5-fold for rhBMP-2, 3.6-fold for rxBMP-4, and up to 22-fold for rhPDGF-bb, whereas rhTGF-beta1 and rhbFGF did not stimulate cell migration in the concentration range tested. In contrast differentiated progenitor cells behave similar to primary human osteoblasts. RhBMP-2, rhPDGF-bb, and rhTGF-beta1 stimulated the migration from 2.2 to 2.4-fold each, while rxBMP-4 and rhbFGF reached only a CI of 1.7-1.6. The effect of rhBMP-2, rxBMP-4, and rhPDGF-bb as chemoattractive proteins for primary human MPC, including the change in response to growth factors after differentiation suggests a functional role for recruitment of MPCs during bone development and remodeling, as well as fracture healing.