Classification of inertial sensor-based gait patterns of orthopaedic conditions using machine learning: A pilot study.

Elderly patients often have more than one disease that affects walking behavior. An objective tool to identify which disease is the main cause of functional limitations may aid clinical decision making. Therefore, we investigated whether gait patterns could be used to identify degenerative diseases using machine learning. Data were extracted from a clinical database that included sagittal joint angles and spatiotemporal parameters measured using seven inertial sensors, and anthropometric data of patients with unilateral knee or hip osteoarthritis, lumbar or cervical spinal stenosis, and healthy controls. Various classification models were explored using the MATLAB Classification Learner app, and the optimizable Support Vector Machine was chosen as the best performing model. The accuracy of discrimination between healthy and pathologic gait was 82.3%, indicating that it is possible to distinguish pathological from healthy gait. The accuracy of discrimination between the different degenerative diseases was 51.4%, indicating the similarities in gait patterns between diseases need to be further explored. Overall, the differences between pathologic and healthy gait are distinct enough to classify using a classical machine learning model; however, routinely recorded gait characteristics and anthropometric data are not sufficient for successful discrimination of the degenerative diseases.

Extraction force, energy and nail deformation for 1.5 m versus 1.0 m intramedullary femoral nail bow design: A biomechanical investigation.

BACKGROUND: The impact of the nail radius of curvature, as one of the most important design features in modern femoral nails on the ease of nail removal, remains unknown. Therefore, the aim of this study was to investigate force, energy, and nail deformation of different nail designs. METHODS: Nail insertion and extraction was performed on six pairs of fresh-frozen human cadaveric femora on a material testing machine with two different nail systems - Trochanter femoral nail ADVANCED™ Nailing System with a radius of curvature of 1.0 m and Proximal Femoral Nail Antirotation System with a radius of curvature of 1.5 m. Deformation was measured after insertion (plastic and elastic deformations) and extraction (plastic deformations). FINDINGS: The peak force during nail removal was significantly lower in the first group (274.5 ± 130.4 N) compared to the second group (695.2 ± 158.8 N, p = 0.001). Plastic deformation was observed in all implants, being significantly larger in the Proximal Femoral Nail Antirotation System (p = 0.027). There was a strong positive correlation between the first peak force during nail removal and nail insertion (r = 0.802, p = 0.002) as well as between extracting energy and insertion energy (r = 0.943, p < 0.001). INTERPRETATION: The results from this study showed that a radius of curvature of 1.0 m is easier to remove from the set of cadaver femora. Furthermore, our findings support the idea of further reducing the nail radius of curvature below 1.0 m in order to more closely match the anatomy of populations with strong-bowed femora.

Biomechanical evaluation of the docking nail concept in periprosthetic fracture fixation around a stemmed total knee arthroplasty.

Intramedullary femoral nails provide an ideal mechanical axis for periprosthetic fracture fixation. Slotted nails allow a connection to a total knee arthroplasty (TKA) stem. This study aims to compare implant and construct stiffness, interfragmentary movement and cycles to failure between an antegrade slotted femoral nail construct docked to a TKA stem and a distal femoral locking plate in a human periprosthetic femoral fracture model. In eight pairs of fresh-frozen human femora with stalked TKA, a 10 mm transverse osteotomy gap was set simulating a Rorabeck type II, Su type I fracture. The femora were pairwise instrumented with either an antegrade slotted nail coupled to the prosthesis stem, or a locking plate. Cyclic testing with a progressively increasing physiologic loading profile was performed at 2 Hz until catastrophic construct failure. Relative movement at the osteotomy site was monitored by means of optical motion tracking. In addition, four-point bending implant stiffness, torsional implant stiffness and frictional fit of the stem-nail connection were investigated via separate non-destructive tests. Intramedullary nails exhibited significantly higher four-point bending and significantly lower torsional implant stiffness than plates, P < 0.01. Increasing difference between nail and stem diameters decreased frictional fit at the stem-nail junction. Nail constructs provided significantly higher initial axial bending stiffness and cycles to failure (200 ± 83 N/mm; 16'871 ± 5'227) compared to plate constructs (93 ± 35 N/mm; 7'562 ± 1'064), P = 0.01. Relative axial translation at osteotomy level after 2'500 cycles was significantly smaller for nail fixation (0.14 ± 0.11 mm) compared with plate fixation (0.99 ± 0.20 mm), P < 0.01. From a biomechanical perspective, the docking nail concept offers higher initial and secondary stability under dynamic axial loading versus plating in TKA periprosthetic fracture fixation.

Surgical Skills Training Using Simulation for Basic and Complex Hip and Knee Arthroplasty.

Skills training is important in an arthroplasty curriculum and can focus either on "part tasks" or on full procedures. The most commonly used simulations in orthopedics including arthroplasty are anatomic specimens, dry bone models, and virtual or other technology-enhanced systems. A course curriculum planning committee must identify the gaps to address, define what learners need to be able to do, and select the most appropriate simulation modality and assessment for delivery. Each simulation must have a clear structure with learning objectives, steps, and take-home messages. Feedback from learners and faculty must be integrated to improve processes and models for future learning.

Screw-in-screw fixation of fragility sacrum fractures provides high stability without loosening-biomechanical evaluation of a new concept.

Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates. Turn-out is detected in up to 20% of the patients. The aim of this study was to evaluate a new screw-in-screw implant prototype for fragility sacrum fracture fixation. Twenty-seven artificial hemipelvises were assigned to three groups (n = 9) for instrumentation of an SI screw, the new screw-in-screw implant prototype, ora transsacral screw. Before implantation, a vertical osteotomy was set in zone 1 after Denis. All specimens were biomechanically tested to failure in upright position. Validated setup and test protocol were used for complex axial and torsional loading applied through the S1 vertebral body to promote turn-out of the implants. Interfragmentary movements were captured via optical motion tracking. Screw motions were evaluated by means of triggered anteroposterior X-rays. Interfragmentary movements and implant motions were significantly higher for SI screw fixation compared to both transsacral and screw-in-screw fixations. In addition, transsacral screw and screw-in-screw fixations revealed similar construct stability. Moreover, screw-in-screw fixation successfully prevented turn-out of the implant that remained during testing at 0° rotation for all specimens. From biomechanical perspective, fragility sacrum fracture fixation with the new screw-in-screw implant prototype provides higher stability than an SI screw, being able to successfully prevent turn-out. Moreover, it combines the higher stability of transsacral screw fixation with the less risky operational procedure of SI screw fixation and can be considered as their alternative treatment option.

Bio-Derived Apatite As a Bone Graft for Vertebral Trauma.

INTRODUCTION: Traumatic spinal injury presents the potential for significant morbidity and mortality, and posterior fixation and fusion with bone grafts is a primary treatment for many vertebral fractures. While iliac crest autograft (ICBG) is considered the gold standard in bone grafting, this carries risks of morbidity at the donor site as well as prolonging surgery time. Bone graft substitutes (BGS) may provide a viable alternative to autograft but there is little published data concerning its use in trauma. Therefore, we conducted this retrospective review to evaluate the outcomes for fusion among patients who have received a BGS during posterolateral fusion (PLF) for vertebral trauma. MATERIALS AND METHODS: This was a retrospective, consecutive patient cohort. Over a six-month period, we identified 27 patients who had undergone PLF for spine trauma and in whom a BGS comprised of bovine-derived apatite was used. All patients had followed the standard of care. The postoperative plain film radiographs at three, six, 12, and (optionally) 24 months were independently assessed by an orthopedic surgeon who was not affiliated with the hospital. RESULTS: We documented a radiographically observed fusion rate of 85% and a successful treatment rate of 92%. There were no adverse events related to the BGS. Patients who received a BGS with ICBG spent significantly longer in surgery than other patients. There were no adverse events related to the BGS. CONCLUSIONS: The spondylodesis rate following surgery in which the BGS was used in PLF, whether alone, mixed with local bone, or mixed with ICBG is comparable to the rates that have been reported for iliac crest autograft in these indications. The data indicates that the BGS provides a useful adjunct in PLF for the treatment of traumatic spine vertebral injuries. The use of BGS also allows for shorter time in surgery, which may reduce resource utilization and thus lower the total costs of the procedure. CLINICAL RELEVANCE: Posterolateral fusion can be obtained with the use of a bio-derived BGS while reducing the time in surgery by avoiding the second procedure necessary to harvest ICBG. This may be advantageous in cases where the surgeon wishes to minimize operating time or when the availability of autograft is limited.

An excellent 5-year survival rate despite a high incidence of distal femoral cortical hypertrophy in a short hip stem.

BACKGROUND: Although reported results on short stems sound very promising, the occurrence of distal femoral cortical hypertrophy is often observed. The aim of the present study was to report 5-year survival data of a commercially available trochanter sparing short stem and investigate the clinical impact of distal femoral cortical hypertrophy on the outcome. METHODS: 123 total hip arthroplasties were performed on 120 patients from April 2008 to May 2010 (mean age 62, range 29-89 years; 71 hips from male patients, 58%). Clinical and radiological data were collected preoperative, at 6 weeks, 1, 2, 3, and 5 years postoperative to assess the outcome. Radiographs taken immediately postoperative as well as 1 and 5 years postoperative were used to identify and assess cortical hypertrophy. RESULTS: 1 stem had to be revised due to aseptic loosening, resulting in a Kaplan-Meier survival analysis with endpoint for stem revision of 99.2% (95% Confidence Interval 94.1-99.9) at 5 years. 96 radiological and 95 clinical follow-ups were analysed 5 years postoperative. 68 (71%) hips showed distal femoral cortical hypertrophy after 5 years. The average Harris Hip Score and Oxford Hip Score improved 33 (standard deviation (SD) 15.1, range 2-70), 18 (SD 12.1, range -10-43) points, respectively. Overall 16% of the patients reported thigh pain, unrelated to the presence of cortical hypertrophy. DISCUSSION: This short stem shows an excellent 5-year survival rate and good clinical outcome despite a high incidence of cortical hypertrophy. However, the question of the mechanism of load transfer arises.

Is suture comparable to wire for cerclage fixation? A biomechanical analysis.

BACKGROUND: Cerclage wire is the current standard for circumferential bone fixation. Advances in technology have improved modern sutures, allowing for expanded utility and broader application. The present study compared the strength and durability of cerclage fixation between modern suture materials and monofilament wire. METHODS: The Surgeon's Knot, the Nice Knot and the Modified Nice Knot, were each tied using three separate suture materials: no. 2 FiberWire (Arthrex, Naples, FL, USA), no. 2 Ultrabraid (Smith & Nephew, Andover, MA, USA) and no. 5 Ethibond (Johnson & Johnson, Somerville, NJ, USA). These sutures were compared with monofilament wire. Sutures were secured around a fixed diameter using three additional half hitches, whereas a 1.2-mm (18 gauge) stainless steel monofilament wire was used for comparison. One fellow and one orthopaedic surgery resident each tied five trials with every knot/material combination. Samples were subjected to cyclic loading and quasi-static load testing. Respectively, cyclic displacement over time and load to failure were analyzed. Clinical failure (3 mm of cyclic displacement) and absolute failure (opening of the knot or material failure) were the outcomes of interest. RESULTS: During cyclic loading, Ethibond displaced significantly less over time compared to monofilament wire (p < 0.003), whereas FiberWire showed no significant difference. Ultrabraid also behaved similar to wire, except displacing significantly more than wire only with the Surgeon's Knot (p = 0.02). During load to failure, Ethibond and FiberWire failed at significantly greater loads than monofilament wire (p < 0.001), whereas Ultrabraid performed similar to wire. Knot types did not appear to impact the results. CONCLUSIONS: High-performance sutures achieve superior results in biomechanical testing under cyclic and quasi-static load compared to monofilament wire, suggesting that they provide an alternative to wire for cerclage fixation with select clinical application. Biomechanical security of suture cerclage is dependent on suture material, although it is not altered significantly by choice of knot. An ex-vivo study with clinical application would further reinforce whether suture cerclage offers a valid alternative to wire cerclage.

Decrease surgery time by using an alternative lateral parapatellar approach for tibia shaft fracture nailing.

INTRODUCTION: Medial parapatellar or transpatellar ligament approaches are commonly used for nail osteosynthesis in tibia shaft fractures. The lower leg is normally in a hanging position to allow guide wire insertion and reaming of the tibia. However, this position complicates fracture reduction and retention, as well as image intensification throughout the procedure. A lateral parapatellar approach with the lower leg in a semi-extended, horizontal position has been previously described for proximal tibial fracture fixation. The purpose of the presented study was to share the lateral parapatellar approach technique used in our institution and to analyse its feasibility for tibia shaft fracture fixation when compared to a medial parapatellar and transpatellar incision technique. MATERIALS AND METHODS: All patients with tibial shaft fractures treated at our institution between 2009 and 2012 by intramedullary nailing through either a transpatellar, a medial parapatellar or a lateral parapatellar approach were reviewed. Demographics, injury pattern and the operative procedure, especially operation and fluoroscopy time, were analysed. RESULTS: 73 patients were enrolled into the study. Twenty-six patients were treated by use of a lateral parapatellar approach, whilst a transpatellar or a medial parapatellar approach was chosen in 29 and 18 cases, respectively. Patients' characteristics were similar regarding gender and body mass index. When compared to the transpatellar (126 ± 30 min) or the medial parapatellar approach (105 ± 29 min), surgical time was significantly shorter in the lateral parapatellar approach group (96 ± 29 min). Likewise, shorter image intensifier time was documented when a lateral parapatellar approach was chosen (211 ± 189 s) compared to the transpatellar (347 ± 204 s) or the medial parapatellar approach (241 ± 222 s). CONCLUSION: The extra-articular semi-extended tibial nailing technique using a lateral parapatellar approach was associated with a significant decrease in time of surgery, while fluoroscopy time was shorter but not significantly different between the three groups.

Clinical application of a minimally invasive cement-augmentable Schanz screw rod system to treat pelvic ring fractures.

PURPOSE: The purpose of this study is to analyze the results using the USS fracture MIS system (DePuy Synthes) to treat instable pelvic ring fractures. As its outstanding feature, it is the only Schanz screw and rod system at present that combines angular stability, perforation/fenestration of the screws for cement-augmentation, a variable screw length, and a large screw diameter. MATERIALS AND METHODS: Retrospective investigation of 134 pelvic ring fractures treated in 2012-2013. Twenty-five patients obtained the abovementioned implant. Besides baseline characteristics of the included patients and the surgical procedure, a clinical/radiological follow-up of six months was analyzed. RESULTS: Dividing the collective into two groups, I high-energy trauma and II fragility fracture of the pelvis, the following results were recorded: group I: ten patients, six male, age 48.4 ± 19.7 years. Mean ISS 41 ± 22.5, fracture classification: AO/OTA type 61 B1/C1/C3 = 1/5/4. Operative treatment: three transiliac internal fixator, seven iliolumbar fixation, one implant was cement-augmented. Group II: 15 patients, 14 female, age 77.5 ± 10.1 years. Fracture classification according to Rommens: FFPII/III/IV = 6/1/8. Operative treatment: eight transiliac internal fixator, seven iliolumbar fixation, 14 implants were cement-augmented. Overall surgical side complications: 16%. Radiological examination: correct positioning of all ilium screws. Follow-up after six month (16 patients): all showed fracture consolidation. One ilium screw was broken close to the connecting clamp. CONCLUSION: The investigated Schanz screw rod system is a suitable implant to broaden the established procedures to stabilize dorsal pelvic ring fractures. TRIAL REGISTRATION: The study is registered at the Clinical Trial Registry University of Regensburg (Number Z-2017-0878-3).

Operative Stabilization of Chest Wall Trauma: Single-Center Report of Initial Management and Long-Term Outcome.

BACKGROUND: Conservative treatment of even severe thoracic trauma including flail chest was traditionally the standard of care. Recently, we reported possible benefits of surgical chest wall stabilization in accordance with other groups. The aim of this study was to critically review our indications and results of internal fixation of rib fractures in the long-term course. METHODS: We retrospectively analyzed the data of a consecutive series of patients with internal rib fracture fixation at our institution from 8/2009 until 12/2014, and we retrospectively studied the late outcome through clinical examination or personal interview. RESULTS: From 1398 patients, 235 sustained a severe thoracic trauma (AIS ≥3). In 23 of these patients, 88 internal rib fixations were performed using the MatrixRIB® system. The median age of these operated patients was 56 years [interquartile range (IQR) 49-63] with a median ISS of 21 [IQR 16-29]. From 18 local resident patients, follow-up was obtained after an average time period of 27.6 (12-68) months. Most of these patients were free of pain and had no limitations in their daily routine. Out of all implants, 5 splint tips perforated the ribs in the postoperative course, but all patients remained clinically asymptomatic. Plate osteosynthesis showed no loss of reduction in the postoperative course. No cases of hardware prominence, wound infection or non-union occurred. CONCLUSIONS: In our carefully selected thoracic trauma patients, locked plate rib fixation seemed to be safe and beneficial not only in the early posttraumatic course, but also after months and years, patients remain asymptomatic and complete recovery as a rule. Trial registration number KEK BASEC Nr. 2016-01679.

Diagnostic challenges and future perspectives in fracture-related infection.

Fracture-related infection (FRI) is one of the most challenging complications in orthopaedic trauma surgery. It has severe consequences for patients and an important socio-economic impact. FRI has distinct properties and needs to be addressed interdisciplinary. Since criteria for the diagnosis of FRI are not standardized, an expert panel recently proposed a definition for FRI. In this review the current diagnostic modalities and an interdisciplinary diagnostic algorithm based on this recently published definition, are presented and future diagnostic techniques discussed. Since to date, there is no single universal diagnostic test available that gives the clinician the definitive diagnosis of FRI, it is mandatory to follow a standardized diagnostic algorithm to correctly diagnose FRI.

Benefits of hardware removal after plating.

Routine implant removal is frequently performed although evidence-based guidelines are lacking. But routinely planned implant removal has significant economic implications and shows considerable complication rates. In general, clinical outcome seems to improve but pain relief after operation is often unpredictable. Even in patients reporting implant-related pain, implant removal does not guarantee relief and may be associated with further complications. The intra- and postoperative complication rate remains very high. Implant removal demonstrates a significant learning curve and unsupervised junior surgeons tend to cause more complications. The need for implant removal may be questioned. Even with the implant in place, contact activities can be resumed. However, a new adequate trauma can create a new fracture independently if there is an implant in-situ or not. It is important to understand the complications and outcomes to be expected with hardware removal to carefully evaluate its indication.

Healthcare-resource utilization associated with radiation to bone across eight European countries: Results from a retrospective study.

BACKGROUND: Bone metastases and lytic lesions due to multiple myeloma are common in advanced cancer and can lead to debilitating complications (skeletal-related events [SREs]), including requirement for radiation to bone. Despite the high frequency of radiation to bone in patients with metastatic bone disease, our knowledge of associated healthcare resource utilization (HRU) is limited. METHODS: This retrospective study estimated HRU following radiation to bone in Austria, the Czech Republic, Finland, Greece, Poland, Portugal, Sweden and Switzerland. Eligible patients were ≥ 20 years old, had bone metastases secondary to breast, lung or prostate cancer, or bone lesions associated with multiple myeloma, and had received radiation to bone between 1 July 2004 and 1 July 2009. HRU data were extracted from hospital patient charts from 3.5 months before the index SRE (radiation to bone preceded by a SRE-free period of ≥ 6.5 months) until 3 months after the last SRE that the patient experienced during the study period. RESULTS: In total, 482 patients were included. The number of inpatient stays increased from baseline by a mean of 0.52 (standard deviation [SD] 1.17) stays per radiation to bone event and the duration of stays increased by a mean of 7.8 (SD 14.8) days. Outpatient visits increased by a mean of 4.24 (SD 6.57) visits and procedures by a mean of 8.51 (SD 7.46) procedures. CONCLUSION: HRU increased following radiation to bone across all countries studied. Agents that prevent severe pain and delay the need for radiation have the potential to reduce the burden imposed on healthcare resources and patients.

Biomechanical investigation of four different fixation techniques in sacrum Denis type II fracture with low bone mineral density.

With increasing life expectancy, fragility fractures of the pelvic ring are seen more frequently. Although their osteosynthesis can be very challenging, specific biomechanical studies for investigation of the fixation stability are still lacking. The aim of this study was to biomechanically evaluate four different fixation methods for sacrum Denis type II fractures in osteoporotic bone. Unstable Denis type II vertical sacrum fractures were created in 16 human pelves. Their osteosynthesis was performed with one sacro-iliac screw, posterior sacral plating, triangular fixation, or spino-pelvic fixation. For that purpose, each pelvis was randomly assigned to two paired groups for treatment with either SI-screw/posterior sacral plating or triangular fixation/spino-pelvic fixation. Each hemi-pelvis was cyclically tested under progressively increasing axial compression. Relative interfragmentary movements were investigated via optical motion tracking analysis. Axial stiffness of triangular fixation was significantly higher versus posterior sacral plating and spino-pelvic fixation (p ≤ 0.022), but not significantly different in comparison to SI-screw fixation (p = 0.337). Cycles to 2, 3, 5, and 8 mm fracture displacement, as well as to 3°, 5°, and 8° gap angle at the fracture site were significantly higher for triangular fixation compared to all other groups (p ≤ 0.041). Main failure mode for all osteosynthesis techniques was screw cutting through the bone, leading loss of fixation stability. From a biomechanical point of view, triangular fixation in sacrum Denis type II fractures demonstrated less interfragmentary movements and should be considered in unstable fragility fractures of the sacrum. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1624-1629, 2018.

A cadaveric biomechanical study comparing the ease of femoral nail insertion: 1.0- vs 1.5-m bow designs.

INTRODUCTION: Anatomic fit of intramedullary nails was suggested by previous studies to improve significantly when the nail radius of curvature (ROC) is closer to the average femoral anatomy. However, no attempt has been made to investigate the impact of different ROC designs on the nail insertion process. Therefore, this biomechanical study quantitatively compared the ease of insertion between femoral intramedullary nails with a 1.0-m and a 1.5-m bow radius. MATERIALS AND METHODS: Long TFN-ADVANCED™ (TFNA, 1.0 m ROC) and Proximal Femoral Nail Antirotation nails (PFNA, 1.5 m ROC) were implanted pairwise into seven paired cadaver femora. All bones were reamed 1.5 mm larger than the nail diameter. Using a material testing machine, intramedullary nailing was then performed stepwise with 20-mm steps and a 10-mm/s insertion rate, and force was measured. The nail deformation caused by the insertion was assessed through 3D computer models built from pre- and post-nailing CT scans. The ease of insertion between TFNA and PFNA nails was quantified in terms of insertion force, insertion energy and nail deformation. RESULTS: There was no significant difference in the peak force generated during nailing between TFNA and PFNA nails (P = 0.731). However, the force measured at the end of insertion (P = 0.002) was significantly smaller in TFNA nails compared to PFNA nails. After implantation, TFNA nails showed significantly smaller deformation when compared to PFNA nails (P = 0.005, both ends aligned). Furthermore, less energy was required to insert TFNA nails; however, the difference was not significant (P = 0.25). CONCLUSIONS: Compared to PFNA nails, a significant decrease in insertion force and nail deformation was found at the end of insertion for TFNA nails. Results suggest that TFNA having a 1.0-m ROC is easier to insert for the set of femora used in this study compared to PFNA with a 1.5-m ROC.

Pathologic fracture and healthcare resource utilisation: A retrospective study in eight European countries.

BACKGROUND: Skeletal-related events (SREs; pathologic fracture [PF], spinal cord compression and radiation or surgery to bone) are common complications of bone metastases or bone lesions and can impose a considerable burden on patients and healthcare systems. In this study, the healthcare resource utilisation (HRU) associated with PFs in patients with bone metastases or lesions secondary to solid tumours or multiple myeloma was estimated in eight European countries. METHODS: Eligible patients were identified in Austria, the Czech Republic, Finland, Greece, Poland, Portugal, Sweden and Switzerland. HRU data were extracted from hospital charts from 3.5 months before the index PF (defined as a PF preceded by a 6.5-month period without a SRE) until 3 months after the last SRE during the study period. Changes from baseline in the number and duration of inpatient stays, number of outpatient visits and number of procedures provided were recorded. RESULTS: Overall, 118 patients with PFs of long bones (those longer than they are wide, e.g. the femur) and 241 patients with PFs of other bones were included. Overall, HRU was greater in patients with long bone PFs than in those with PFs of other bones. A higher proportion of patients with long bone PFs had multiple SREs (79.7%), and more of their SREs were considered to be linked (73.4%) compared with patients with PFs of other bones (51.0% and 47.2%, respectively). CONCLUSION: The increased number and duration of inpatient stays for PFs of long bones compared with those for PFs of other bones may be due in part to the requirement for complicated and lengthy rehabilitation in patients with long bone PFs. Implementing strategies to delay or reduce the number of PFs experienced by patients with bone metastases or lesions may therefore reduce the associated HRU and patient burden.

Knee joint kinematics with dynamic augmentation of primary anterior cruciate ligament repair - a biomechanical study.

BACKGROUND: Dynamic augmentation of anterior cruciate ligament tears seems to reduce anteroposterior knee translation close to the pre-injury level. The aim of the present study is to biomechanically investigate the course of translation during a simulated early post-operative phase. It is hypothesized that anteroposterior translation is maintained at the immediate post-operative level over a simulated rehabilitation period of 50'000 gait cycles. METHODS: Eight fresh-frozen human cadaveric knee joints from donors with a mean age of 35.5 (range 25-40) years were subjected to 50'000 cycles of 0°-70°-0° flexion-extension movements in a custom-made test setup. Anteroposterior translation was assessed with simulated Lachman/KT-1000 testing in 0°, 15°, 30°, 60° and 90° of flexion in knee joints treated with the novel technique initially and after 50'000 cycles testing. Statistical analysis was performed using the Wilcoxon Signed-Rank Test. The level of significance was set at p = 0.05. RESULTS: Anteroposterior translation changed non-significantly for all flexion angles between cycle 0 and 50'000 (p = 0.39 to p = 0.89), except for 30° flexion, where a significant increase by 1.4 mm was found (p = 0.03). CONCLUSION: Increase in anteroposterior translation of knees treated with this dynamic augmentation procedure is low. The procedure maintains translation close to the immediate post-operative level over a simulated rehabilitation period of 50'000 gait cycles and therefore supports anterior cruciate ligament repair during biological healing.