Wound infection following implant removal of foot, ankle, lower leg or patella; a protocol for a multicenter randomized controlled trial investigating the (cost-)effectiveness of 2 g of prophylactic cefazolin compared to placebo (WIFI-2 trial).

BACKGROUND: Elective implant removal (IR) after fracture fixation is one of the most common procedures within (orthopedic) trauma surgery. The rate of surgical site infections (SSIs) in this procedure is quite high, especially below the level of the knee. Antibiotic prophylaxis is not routinely prescribed, even though it has proved to lower SSI rates in other (orthopedic) trauma surgical procedures. The primary objective is to study the effectiveness of a single intravenous dose of 2 g of cefazolin on SSIs after IR following fixation of foot, ankle and/or lower leg fractures. METHODS: This is a multicenter, double-blind placebo controlled trial with a superiority design, including adult patients undergoing elective implant removal after fixation of a fracture of foot, ankle, lower leg or patella. Exclusion criteria are: an active infection, current antibiotic treatment, or a medical condition contraindicating prophylaxis with cefazolin including allergy. Patients are randomized to receive a single preoperative intravenous dose of either 2 g of cefazolin or a placebo (NaCl). The primary analysis will be an intention-to-treat comparison of the proportion of patients with a SSI at 90 days after IR in both groups. DISCUSSION: If 2 g of prophylactic cefazolin proves to be both effective and cost-effective in preventing SSI, this would have implications for current guidelines. Combined with the high infection rate of IR which previous studies have shown, it would be sufficiently substantiated for guidelines to suggest protocolled use of prophylactic antibiotics in IR of foot, ankle, lower leg or patella. Trial registration Nederlands Trial Register (NTR): NL8284, registered on 9th of January 2020, https://www.trialregister.nl/trial/8284.

Expanding the horizons of clinical applications of proximal humerus locking plates in the lower extremities: A technical note.

Pre-contoured anatomical locking plates were designed to address the clinical need of fixing small epiphyseal segments with a larger number of screws. Those plates match the contour and shape of a variety of bones allowing for optimal buttress properties. The aim of this manuscript is to highlight the benefits of applying proximal humerus locking plates in the fixation of lower extremity bones. Although designed for the proximal humerus, the low-profile plate shape and anatomic contour also provides versatile use in certain areas of the lower extremity. This technical narrative highlights the versatile and reliable use of this plate for other anatomical areas than the one to which it has been originally conceived.

Retrospective evaluation of perioperative and short term clinical outcomes in appendicular long bone skeleton fractures repaired via the string of pearls (SOP) locking plate system.

BACKGROUND: Internal plate fixation and, more recently, locking plate fixation are commonly used in the repair of fractures in small animal surgery. This retrospective study reviewed the use of the String of Pearls locking plate system in the fixation/repair of appendicular long bone skeleton fractures in 31 small animal veterinary patients (33 fractures). RESULTS: Major complications necessitating revision surgery occurred in 7/33 (21%), with implant failure as the inciting cause in all cases. Variables corresponding to an unsuccessful outcome were evaluated, and a correlation was found with plates placed in a bridging manner (placed without rigid anatomic reconstruction, p = 0.02) and length of follow-up (p = 0.01). CONCLUSIONS: The SOP plating system can be used in the repair of appendicular longbone skeletal fractures, however, the authors propose that adjunct fixation, such as intramedullary pin, double plating, or external coaptation would likely improve results and should be considered imperative in cases in which anatomic reconstruction is either not desirable or achievable.

Prophylactic negative pressure wound therapy after lower extremity fracture surgery: a pilot study.

PURPOSE: Infectious complications following lower extremity fracture surgery are a major concern and account for a substantial socio-economic burden to society. The aim of this pilot study was to investigate the feasibility of a new portable single-use negative pressure wound therapy device in patients undergoing major foot ankle surgery. METHODS: Patients undergoing major foot ankle fracture surgery at a single level 1 trauma centre were eligible for this prospective case series. Patient characteristics were collected, as were fracture and surgical characteristics. Primary outcome was surgical site infection within 30 days as classified by the criteria from the Centers for Disease Control and Prevention. Patients in the prospective cohort were case-matched with a historical cohort from the same institution. RESULTS: Sixty patients were included. In seven patients, the NPWT failed and treatment was ceased. Mean age was 44 years and 85% was ASA 1; 43% of the patients were actively smoking. Indications for surgery were midfoot, calcaneal, talar, and ankle fractures. In 53 patients, four (7.5%) surgical site infections occurred, two superficial (3.3%) and two (3.3%) deep infections. For 47 patients, a match was available. The incidence of surgical site infection did not statistically significantly differ between the prospective cohort and retrospective matched cohort (4.3 versus 14.9%, p = 0.29, respectively). This was also the case when looking at superficial and deep surgical site infections separately (0 versus 8.5%, p = 0.08, and 4.3 versus 6.4%, respectively). CONCLUSION: We have observed surgical site infections in 7.5% of the patients with the use of prophylactic negative pressure wound therapy. The incidence of surgical site infections was not statistically significantly lower compared to a matched historical cohort.

Implant and limb survival after resection of primary bone tumors of the lower extremities and reconstruction with mega-prostheses fifty patients followed for a mean of forteen years.

PURPOSE: Previous studies reported variable outcome and failure rates after mega-prosthetic reconstructions in the lower extremities. The purpose of this study was to make a long-term single-center evaluation of patients treated with limb-sparing surgery and reconstruction with mega-prostheses in the lower extremities. METHODS: We identified 50 patients (osteosarcoma (n = 30), chondrosarcoma (n = 9), osteoclastoma (n = 6), Ewing sarcoma (n = 4), angiosarcoma (n = 1)), who underwent limb-sparing reconstruction of the lower extremities (proximal femur (n = 9), distal femur (n = 29), proximal tibia (n = 9), and the entire femur (n = 3)) between 1985 and 2005. Surviving patients not lost to follow-up were evaluated using the MSTS score. Causes of failure were classified according to the Henderson classification. Kaplan-Meier survival analysis was used for evaluation of patient, prosthesis, and limb survival. RESULTS: Twenty-eight patients were alive at follow-up. Fifty-four percent had revision surgery (n = 27). The ten year patient survival was 60% (95%CI 46-74%); the ten year implant survival was 24% (95%CI 9-41%), and the ten year limb survival rate was 83% (95%CI 65-96%). Type 1 failure occurred in 9%, type 2 in 16%, type 3 in 28%, type 4 in 18%, and type 5 in 3%. Mean MSTS score was 21 (range, 6-30), representing a median score of 71%. CONCLUSIONS: Our long-term results with mega-prostheses justify the use of limb-salvage surgery and prosthetic reconstruction. Our results are fully comparable with other findings, with regard to limb and prosthesis survival, but also with regard to functional outcome.

Abaloparatide versus teriparatide: a head to head comparison of effects on fracture healing in mouse models.

Background and purpose - Teriparatide accelerates fracture healing in animals and probably in man. Abaloparatide is a new drug with similar although not identical effects on the teriparatide receptor. Given at 4 times the teriparatide dose in a human osteoporosis trial, abaloparatide increased bone density more than teriparatide, and both reduced fracture risk. We investigated in mice whether abaloparatide stimulates fracture healing, and if it does so with the suggested dose effect relation (4:1). Patients and methods - In a validated mouse model for metaphyseal healing (burr hole with screw pull-out), 96 mice were randomly allocated to 11 groups: control (saline), teriparatide or abaloparatide, where teriparatide and abaloparatide were given at 5 different doses each. In a femoral shaft osteotomy model, 24 mice were randomly allocated to 3 groups: control (saline), teriparatide (15 µg/kg) or abaloparatide (60 µg/kg). Each treatment was given daily via subcutaneous injections. Results were evaluated by mechanical testing and microCT. Results - In the metaphyseal model, a dose-dependent increase in screw pull-out force could be seen. In a linear regression analysis (r = 0.78) each increase in ln(dose) by 1 (regardless of drug type) was associated with an increase in pull-out force by 1.50 N (SE 0.18) (p < 0.001). Changing drug from teriparatide to abaloparatide increased the force by 1.41 N (SE 0.60; p = 0.02). In the diaphyseal model, the callus density was 23% (SD 10), 38% (SD 10), and 47% (SD 2) for control, for teriparatide and abaloparatide respectively. Both drugs were significantly different from controls (p = 0.001 and p = 0.008), but not from each other. Interpretation - Both drugs improve fracture healing, but in these mouse models, the potency per µg of abaloparatide seems only 2.5 times that of teriparatide, rather than the 4:1 relation chosen in the clinical abaloparatide-teriparatide comparison trial.

A Comparison of Vascularized Free Fibular Flaps and Nonvascularized Fibular Grafts for Reconstruction of Long Bone Defects after Tumor Resection.

Background The use of the fibula autograft has been a reliable method in the reconstruction of long bone defects after tumor resection. The objective of this study was to report the outcomes fibular grafting in terms of graft union, functional score, complications, and oncologic outcome. Methods A retrospective review of patients with fibular grafting after tumor resection was done from January 1, 1993 to December 31, 2013. The primary outcome was graft union and the revised musculoskeletal tumor society scoring system (MSTS score). The secondary outcomes were oncologic outcomes, complications, and the factors associated with graft union. Results A total of 52 patients with a mean follow-up of 42 months (SD, 33; range, 12-132 months) were included. The overall union for all fibular grafts was 37 of 52. The use of vascularized free fibula flaps had a higher union rate compared with nonvascularized fibula grafts. The use of a vascularized free fibular flap was four times likely to unite (95% CI 1.1-12.8, p = 0.039) compared with nonvascularized fibular grafts. The mean MSTS score in 36 patients was 82.5 (SD, 12.9) at 35 months from surgery (SD, 30). A total of 39 complications were present in 29 patients. On final follow-up, 45 of 52 patients were alive, six patients had died of disease and one died of other causes. Conclusion A higher union rate was achieved using vascularized free fibular flaps compared with nonvascularized fibular grafts for long bone reconstruction after tumor resection. There was no difference in terms of MSTS score between the two types of grafts.

Health related quality of life in adolescent and young adult survivors of lower extremity bone tumors.

BACKGROUND: Dramatic increases in survival rates have led to increased interest regarding the health related quality of life (HRQOL) of adolescent and young adult survivors of bone tumors. This study investigated HRQOL and physical disability in adolescent and young adult survivors of lower extremity bone tumors as a function of type of surgical intervention, gender, and age at assessment. PROCEDURE: Twenty-eight participants (age range 18-32 years) completed three generic and one disease-specific measures of HRQOL and a measure of physical disability. For analysis, surgical intervention was grouped into limb sparing surgeries (LS; allograft fusion and endoprosthesis) and ablative surgeries (AMP; amputation or Van Nes rotationplasty). Age at study was grouped into ≤ 25 years of age and ≥ 26 years of age. The MOS-SF-36, HUI2, HUI3, and EORTC-QLQ-C30 were used to measure HRQOL and the TESS was used to assess physical disability. RESULTS: Survivors reported HRQOL equivalent to the general population, with the exception of physical functioning. LS reported poorer HRQOL than AMP participants for emotional functioning and fatigue. Males reported better HRQOL compared with females for overall HRQOL, general health, physical functioning, and social functioning. Finally, younger participants generally reported better HRQOL than older participants for overall HRQOL and physical functioning. CONCLUSIONS: This study identifies LS surgical intervention, female gender and older age as risk factors for reduced HRQOL in adolescent and young adult survivors of lower extremity bone tumors. This study also provides information about what instrument may be most useful in identifying these specific difficulties and subgroups.

Principles of rotationplasty.

Rotationplasty is a reconstructive, limb-sparing option for management of lower extremity bone deficiency. This technique involves an intercalary resection, followed by 180° rotation of the distal limb to allow the ankle to function as a knee joint when it is fitted with a modified below-knee prosthesis. Gait analysis and functional outcome studies have reported favorable results with rotationplasty compared with those of above-knee amputation. Moreover, patient satisfaction with rotationplasty is higher than with other limb salvage procedures. The primary drawback of this procedure is patient acceptance of the limb's appearance.

[Treatment outcome of patients with bone tumors after limb salvage surgery].

In 336 patients with various tumors of the limb bones underwent limb sparing surgery with different kind of reconstructions. The oncological results of the treatment of these patients have been analysed. Local relapse after limb sparing interventions because of extremities bone tumors developed in 4,17% of all cases. In most cases, local recurrences have been observed in patients with bone sarcomas high degree of malignancy (7,14%) and low degree of malignancy (2,82%). In 57,1% of cases, local recurrences developed in patients with osteogenic sarcoma IIB stage. The appearance of local recurrence was a bad prognostic factor for patients with bone sarcomas high grade, because it reduced 5-year survival rate almost 2 times. The overall 5-year survival of patients with bone sarcomas high grade of malignancy were (59,67 +/- 5,69)%, and 5-year relapse-free survival rate--(55,23 +/- 5,52)%. Local recurrences more often developed after the use of distraction method of surgery--in 16% of all reconstructive operations, including 12% of the cases with bone tumors of high degree of malignancy, which should be considered when choosing this method of reconstruction.

Allograft Alone vs. Allograft with Intramedullary Vascularized Fibular Graft for Lower Extremity Bone Cancer: A Systematic Review and Meta-Analysis.

BACKGROUND: Limb salvage surgery has become a first-line treatment in the setting of lower extremity cancer. Despite a multitude of techniques, the most effective modality for osseous reconstruction has not been described. We aim to examine outcomes of allograft reconstruction alone compared to an allograft combined with a vascularized fibula graft (VFG) (Capanna Technique) through a meta-analysis of the literature. METHODS: A systematic review of the literature was conducted through the online databases PubMed, Embase, and Web of Science, examining articles utilizing an allograft with or without an intramedullary VFG for the reconstruction of lower extremity osseous defects following oncological resection. A meta-analysis examined outcomes, including nonunion, infection, fractures, explantation, and functional limb status, that were evaluated dependent upon reconstructive modality. RESULTS: Twenty-five articles were deemed appropriate for inclusion. The allograft with VFG group had considerably lower rates of nonunion (13%) in comparison to the allograft alone group (21.4%) (p < .001). Rates of infection (7.9% vs. 9%, respectively) and fracture (19.6% vs. 19.1%) were not statistically different. The allograft with VFG group also had significantly lower rates of explantation (6.57%) compared to the allograft alone cohort (18.11%) (p < .001). Functional outcomes were similar across groups as measured by Musculoskeletal Tumor Society scores (88.22% vs. 87.77%). CONCLUSIONS: Allograft reconstruction with a supplementary inlay VFG decreases the risk of nonunion and explantation compared to allograft alone reconstruction in the setting of oncological resection of the osseous lower extremity. This technique warrants increased consideration in the operative planning of lower limb reconstruction following tumor extirpation.

[Long bone fractures in cattle: A retrospective study of treatment and outcome in 194 cases]. / Frakturen der langen Röhrenknochen beim Rind: Eine retrospektive ­Auswertung der Therapie und des Verlaufs bei 194 Tieren.

INTRODUCTION: The present retrospective study investigated the localization, cause, treatment and healing of long bone fractures in cattle. Over a period of ten years, medical records of 194 cattle of all ages with a long bone fracture, presented at the Clinic for Ruminants with Ambulatory and Herd Health Services at LMU Munich, were evaluated. The majority of patients (n = 131, 67.5%) were younger than two weeks of age. Of these, 118 calves sustained the fracture on the day of birth (60.8%). An obstetrical assistance was found in 57.4% (n = 58) of birth-related cases as a fracture cause. The femur was most frequently affected in calves aged up to two weeks (n = 35; 26.7%). The second most frequent fractures occurred in the metacarpus (n = 31; 22.9%) in this age group, followed by metatarsus (n = 28; 21.4%) and tibia (n = 27; 20.6%). Fractures of the antebrachium (n = 9; 6.9%) and the humerus were rare (n = 1; 0.8%). A total of 194 patients were diagnosed with 50 femur fractures (25.8%), 53 metacarpal fractures (27.3%), 43 metatarsal fractures (22.2%), 30 tibial fractures (15.5%), 11 antebrachial fractures (5.7%) and 7 humeral fractures (3.6%). Of the 194 animals, 78 (40.2%) had to be euthanized, 42 of them (53.8%) without treatment. In 150 patients, treatment was initiated, of which 110 patients (73.3%) were dismissed healthy from the clinic. Among the conservative treatment methods were stall rest, casts, casts combined with a U-shaped metal rail (walking casts) and the Thomas splint. Surgical therapy (internal fixation with plates or screws, transfixation pin casts) was used to treat 65 animals (33.5%). While 86.9% (74 out of 85) of the conservatively treated animals left the clinic alive, it were only 58.1% (36 out of 65) animals after surgical treatment. In the newborn calves, colostrum supply had a significant effect on the success of the treatment. If the gamma-glutamyl transferase concentration was below 200 IU/L in the calves aged under 4 days, the healing rate was significantly different from the cure rate of sufficiently immunized patients (26.9% (7 out of 26) vs. 65.3% (47 out of 72), P = 0.001).

INTRODUCTION: La présente étude rétrospective a examiné la localisation, la cause, le traitement et la guérison des fractures des os longs chez les bovins. Sur une période de dix ans, les dossiers médicaux de 194 bovins de tous âges souffrant d'une fracture d'un os long et présentés à la Clinique pour les ruminants avec services ambulatoires et services de santé du troupeau à la Ludwig-Maximilians-Universität de Munich, ont été évalués. La majorité des patients (n = 131, 67,5%) étaient âgés de moins de deux semaines. Parmi ceux-ci, 118 veaux ont subi la fracture le jour de leur naissance (60,8%). Une assistance obstétricale par traction a été trouvée dans 57,4% (n = 58) des cas liés à la naissance en tant que cause de fracture. Le fémur était le plus souvent touché chez les veaux âgés de moins de deux semaines (n = 35; 26,7%).). La deuxième fracture la plus fréquente survenait au niveau du métacarpe (n = 31; 22,9%)), suivi du métatarse (n = 28; 21,4%) et du tibia (n = 27; 20,6%).). Les fractures de l'antebrachium (n = 9; 6,9%) et de l'humérus étaient rares (n = 1; 0,8%). Au total, sur les 194 patients ont a diagnostiqué 50 fractures du fémur (25,8%), 53 fractures du métacarpe (27,3%), 43 fractures du métatarse (22,2%), 30 fractures du tibia (15,5%), 11 fractures antébrachiales (5,7%) et 7 fractures de l'humérus (3,6%). Sur les 194 animaux, 78 (40,2%) ont dû être euthanasiés, dont 42 (53,8%) sans traitement. Deux animaux (1.0%) ont été abattus. Sur les 150 patients traités, 36 (24.0%) ont été euthanasiés et 4 ont péri. 110 patients (73,3%) ont été renvoyés en bonne santé de la clinique. Parmi les méthodes de traitement conservatif figurent le repos en stalle, les plâtres en résine, les plâtres en résine combinés à une attelle en métal en forme de U comme attelle de marche et l'attelle de Thomas. Un traitement chirurgical (fixation interne à l'aide de plaques et/ou de vis de traction, broches de transfixion avec pont en matière synthétique) a été utilisé pour traiter 65 animaux (33,5%). Alors que 86,9% (74 sur 85) des animaux traités de manière conservatrice ont quitté la clinique en vie, ce ne sont que 58,1% (36 sur 65) des animaux après traitement chirurgical. Chez les veaux nouveau-nés, l'apport de colostrum a eu un effet significatif sur le succès du traitement. Si la concentration de gamma-glutamyl transférase était inférieure à 200 UI / L chez les veaux âgés de moins de 4 jours, le taux de guérison était significativement différent du taux de guérison de patients suffisamment immunisés (26,9% (7 sur 26) contre 65,3% (47 sur 72), p = 0,001).

Hypoalbuminemia Is an Independent Risk Factor for 30-Day Mortality, Postoperative Complications, Readmission, and Reoperation in the Operative Lower Extremity Orthopaedic Trauma Patient.

INTRODUCTION: Malnutrition, as indicated by hypoalbuminemia, is known to have detrimental effects on outcomes after arthroplasty, geriatric hip fractures, and multiple general surgeries. Hypoalbuminemia has been examined in the critically ill but has largely been ignored in the orthopaedic trauma literature. We hypothesized that admission albumin levels would correlate with postoperative course in the nongeriatric lower extremity trauma patient. METHODS: Patients with lower extremity (including pelvis and acetabulum) fracture who underwent operative intervention were collected from the ACS-NSQIP database. Patients younger than 65 years were included. Patient demographic data, complications, length of stay, reoperation rate, and readmission rate were collected, and patient modified frailty index scores were calculated. Poisson regression with robust error variance was then conducted, controlling for potential confounders. RESULTS: Five thousand six hundred seventy-three patients with albumin available were identified, and 29.6% had hypoalbuminemia. Hypoalbuminemic patients had higher rates of postoperative complications [9.3% vs. 2.6%; relative risk (RR) 1.63] including increased rates of: mortality (3.2% vs. 0.4%; RR 4.86, 95% confidence interval 2.66-8.87), sepsis (1.5% vs. 0.5%, RR 2.35), and reintubation (2.3% vs. 0.4%; RR 3.84). Reoperation (5.5% vs. 2.6%, RR 1.74) and readmission (11.4% vs. 4.1%; RR 2.53) rates were also higher in patients with low albumin. CONCLUSION: Hypoalbuminemia is a powerful predictor of acute postoperative course and mortality after surgical fixation in nongeriatric, lower extremity orthopaedic trauma patients. Admission albumin should be a routine part of the orthopaedic trauma workup. Further study into the utility of supplementation is warranted, as this may represent a modifiable risk factor. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Improved Surface-Based Registration of CT and Intraoperative 3D Ultrasound of Bones.

The intraoperative registration of preoperative CT volumes is a key process of most computer-assisted orthopedic surgery (CAOS) systems. In this work, is reported a new method for automatic registration of long bones, based on the segmentation of the bone cortical in intraoperative 3D ultrasound images. A bone classifier was developed based on features, obtained from the principal component analysis of the Hessian matrix, of every voxel in an intraoperative ultrasound volume. 3D freehand ultrasound was used for the acquisition of the intraoperative ultrasound volumes. Corresponding bone surface segmentations in ultrasound and preoperative CT imaging were used for the intraoperative registration. Validation on a phantom of the tibia produced encouraging results, with a maximum mean segmentation error of 0.34⁡mm (SD=0.26⁡mm) and a registration accuracy error of 0.64⁡mm (SD=0.49⁡mm).

Motorcyclists and pillion passengers with open lower-limb fractures: a study using TARN data 2007-2014.

Introduction We aimed to identify population demographics of motorcyclists and pillion passengers with isolated open lower-limb fractures, to ascertain the impact of the revised 2009 British Orthopaedic Association/British Association of Plastic Reconstructive and Aesthetic Surgeons joint standards for the management of open fractures of the lower limb (BOAST 4), in terms of time to skeletal stabilisation and soft-tissue coverage, and to observe any impact on patient movement. Methods Retrospective cohort data was collected by the Trauma Audit and Research Network (TARN). A longitudinal analysis was performed between two timeframes in England (pre-and post-BOAST 4 revision): 2007-2009 and 2010-2014. Results A total of 1564 motorcyclists and 64 pillion passengers were identified. Of these, 93% (1521/1628) were male. The median age for males was 30.5 years and 36.7 years for females. There was a statistically significant difference in the number of patients who underwent skeletal stabilisation (49% vs 65%, P < 0.0001), the time from injury to skeletal stabilisation (7.33 hours vs 14.3 hours, P < 0.0001) and the proportion receiving soft-tissue coverage (26% vs 43%, P < 0.0001). There was no difference in the time from injury to soft-tissue coverage (62.3 hours vs 63.7 hours, P = 0.726). The number of patients taken directly to a major trauma centre (or its equivalent) increased between the two timeframes (12.5% vs, 41%, P < 0.001). Conclusions Since the 2009 BOAST 4 revision, there has been no difference in the time taken from injury to soft-tissue coverage but the time from injury to skeletal stabilisation is longer. There has also been an increase in patient movement to centres offering joint orthopaedic and plastic care.

Intramedullary nailing of the lower extremity: biomechanics and biology.

The intramedullary nail or rod is commonly used for long-bone fracture fixation and has become the standard treatment of most long-bone diaphyseal and selected metaphyseal fractures. To best understand use of the intramedullary nail, a general knowledge of nail biomechanics and biology is helpful. These implants are introduced into the bone remote to the fracture site and share compressive, bending, and torsional loads with the surrounding osseous structures. Intramedullary nails function as internal splints that allow for secondary fracture healing. Like other metallic fracture fixation implants, a nail is subject to fatigue and can eventually break if bone healing does not occur. Intrinsic characteristics that affect nail biomechanics include its material properties, cross-sectional shape, anterior bow, and diameter. Extrinsic factors, such as reaming of the medullary canal, fracture stability (comminution), and the use and location of locking bolts also affect fixation biomechanics. Although reaming and the insertion of intramedullary nails can have early deleterious effects on endosteal and cortical blood flow, canal reaming appears to have several positive effects on the fracture site, such as increasing extraosseous circulation, which is important for bone healing.

Reference marker stability in computer aided orthopedic surgery: a biomechanical study in artificial bone and cadavers.

INTRODUCTION: In computer assisted orthopaedic surgery, rigid fixation of the Reference Marker (RM) system is essential for reliable computer guidance. A minimum shift of the RM can lead to substantial registration errors and inaccuracies in the navigation process. Various types of RM systems are available but there is little information regarding the relative stabilities of these systems. The aim of this study was to test the rotational stability of three commonly used RM systems. MATERIALS AND METHODS: One hundred and thirty Synbones and 15 cadavers were used to test the rotational stability of three different RM systems (Schanz' screw, RM B and RM C adjustment systems). Using a specially developed testing device, the peak torque sustained by each RM system was assessed in various anatomical sites. RESULTS: Comparison of means for Synbone showed that the RM C was the most stable (mean peak torque 5.60 +/- 1.21 Nm) followed by the RM B system (2.53 +/- 0.53 Nm) and the RM A (0.77 +/- 0.39 Nm) (p<0.01). The order of stability in relation to anatomical site was femoral shaft, distal femur, tibial shaft, proximal tibia, anterior superior iliac spine, iliac crest and talus. Results from the cadaver experiments showed similar results. Bi-cortical fixation was superior to mono-cortical fixation in the femur (p<0.01) but not the tibia (p=0.22). CONCLUSION: The RM system is the vital link between bone and computer and as such the stability of the RM is paramount to the accuracy of the navigation process. In choosing RM systems for computer navigated surgery surgeons should be aware of their relative stability. Anatomical site of RM placement also affect the stability. Mono-cortical fixation is generally less stable than bi-cortical.

[Treatment principles in bone reconstruction and limb lengthening of the lower extremity].

Limb length discrepancies, axis deviations and bone loss on a congenital, traumatic or infectious basis are treated with restoration of axis and bone elongation. The intention is to improve gait and function, to relieve pain caused by imbalance in the musculoskeletal system and to prevent degenerative joint disease. Modern motorized intramedullary nails spare the patients for external fixators, and thus complications are being reduced. X-ray, CT-based planning and a thorough clinical examination is essential for a good result. Complications are frequent, and treatment can be lengthy. Modern techniques have made treatment more gentle and allow a normal daily life during treatment and rehabilitation.

Correction of deformities in children using the Taylor spatial frame.

The Taylor spatial frame is a unique external fixator. Despite its growing popularity, few reports on its use have been published. We evaluated the effectiveness of the Taylor spatial frame in the treatment of various deformities in 31 children and adolescents. All but one patient were anatomically corrected. Complications included superficial pin tract infection (45%), three fractures of the femoral regenerate, transient peroneal palsy, and injury to the genicular artery. Despite many challenging problems, our results compared favorably with the results achieved by others. We believe that the Taylor spatial frame is a very capable and accurate fixator for the precise correction of complex deformities.