Accuracy of 4 Different Methods for Estimation of Remaining Growth and Timing of Epiphysiodesis.

BACKGROUND: The calculation of remaining growth in children and the timing of epiphysiodesis in those with leg-length discrepancy (LLD) is most often done with 4 methods: the Green-Anderson, White-Menelaus, Moseley straight-line graph, and multiplier methods. The aims of this study were to identify the most accurate method with use of bone age or chronological age and to evaluate the influence of including inhibition in the calculations. METHODS: One hundred and ninety-one children (10 to 17 years of age) with LLD who underwent surgical closure of the growth plate and were followed until skeletal maturity were identified from a local health register. Patients had at least 2 leg-length examinations with simultaneous bone-age assessments (according to the Greulich and Pyle method), with the last examination performed ≤6 months before surgery. The accuracy of each method was calculated as the mean absolute prediction error (predicted leg length - actual leg length at maturity) for the short leg, the long leg, and the LLD. Comparisons were made among the 4 methods and among calculations made with chronological age versus bone age and those made with versus those without incorporation of a reduced growth rate (inhibition) of the short leg compared with the long leg. RESULTS: The White-Menelaus method with use of bone age and a fixed inhibition rate was the most accurate method, with a prediction error of 1.5 ± 1.5 cm for the short leg, 1.0 ± 1.2 cm for the long leg, and 0.7 ± 0.7 cm for the LLD. Pairwise comparison of short-leg length and LLD according to the White-Menelaus and other methods showed that they were significantly different (p ≤ 0.002). The calculated inhibition rate did not increase accuracy. CONCLUSIONS: The White-Menelaus method used with bone age and constant inhibition should be the preferred method when predicting remaining growth and the timing of epiphysiodesis in children between 10 and 17 years of age. One examination is in most cases sufficient for the preoperative clinical investigation when chronological age and bone age are concordant. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

General and local predictors of mandibular cortical bone morphology in adult females and males: the seventh survey of the Tromsø Study.

OBJECTIVES: To analyze factors predicting mandibular cortical width (MCW) and mandibular cortical index (MCI) in adult females and males. MATERIAL AND METHODS: Data on 427 females and 335 males aged 40-84 from The Tromsø study: Tromsø7 were used. T-score, age, menopausal status (for females), remaining teeth, and periodontal status were analyzed in linear and logistic regression analyses as predictors of MCW and MCI, respectively. RESULTS: T-score, age, and the number of remaining teeth significantly predicted MCW in females but not males. Standardized ß coefficients were 0.286, -0.231, and 0.131, respectively. The linear regression model explained 24% of MCW variation in females. MCI in females was significantly predicted by T-score, age, and remaining teeth with the Wald values of 9.65, 6.17, and 5.83, respectively. The logistic regression model explained 16.3-23% of the variation in MCI in females. In males, T-score was the only significant predictor of the eroded cortex, and the logistic model explained only 4.3-5.8% of the variation in MCI. CONCLUSIONS: The T-score demonstrated a stronger relationship with MCW and MCI than other factors in females, which supports the usefulness of those indices for osteoporosis screening. Conversely, the T-score exhibited no association with MCW and remained the only significant predictor of MCI in males, yet to a lesser extent than in females. CLINICAL RELEVANCE: Understanding factors affecting mandibular cortical morphology is essential for further investigations of MCW and MCI usefulness for osteoporosis screening in females and males.

Diagnostic efficacy of radiomorphometric indices for predicting osteoporosis in a Norwegian population in the Tromsø Study: Tromsø7.

OBJECTIVE: The aim of this study was to investigate the diagnostic efficacy of the radiomorphometric indices of mandibular cortical width (MCW) and mandibular cortical index (MCI) of cortical erosion for osteoporosis screening in adults (≥40 years) and older adults (≥65 years) to determine whether adding a fracture risk assessment tool (FRAX) would improve efficacy. STUDY DESIGN: One observer measured MCW and assessed MCI on dental panoramic radiographs acquired for patients in the Tromsø study. These indices, alone and with FRAX scores, were evaluated for efficacy in predicting osteoporosis, which was diagnosed by bone density measurement at the femoral necks with dual-energy X-ray absorptiometry. RESULTS: MCW ≤3 mm and MCI indicating heavily eroded cortices (C3) had accuracies of 68.8% and 83.6%, respectively, in identifying osteoporosis. In females >65 years, MCW ≤3 mm and C3 produced higher sensitivities but lower specificities, with slightly lower accuracies (61.4% and 79.8%, respectively) compared with all females. The addition of FRAX scores >15% improved the accuracy of MCW ≤3 mm (81.7%) and C3 (87.9%), resulting in high specificity (86.6% and 95.4%). Combining MCW ≤3 mm or C3 with FRAX >15% increased the probabilities of detecting osteoporosis by increasing positive likelihood ratios. CONCLUSIONS: MCW ≤3 mm or MCI C3, when combined with FRAX >15%, showed superior diagnostic efficacy, with high specificity in detecting females without osteoporosis.

Postoperative changes in vertical ground reaction forces, walking barefoot and with ankle-foot orthoses in children with Cerebral Palsy.

BACKGROUND: Children with cerebral palsy often have problems to support the body centre of mass, seen as increased ratio between excessive vertical ground reaction forces during weight acceptance and decreased forces below bodyweight in late stance. We aimed to examine whether increasing ankle range of motion through surgery and restraining motion with ankle-foot orthoses postoperatively would have impact on the vertical ground reaction force in weight acceptance and late stance. METHODS: Ground reaction forces were recorded from 24 children with bilateral and 32 children with unilateral cerebral palsy, each measured walking barefoot before and after triceps surae lengthening. Postoperatively, the children were also measured walking with ankle-foot orthoses. Changes in vertical ground reaction forces between the three conditions were evaluated with functional curve and descriptive peak analyses; accounting for repeated measures and within-subject correlation. FINDINGS: After surgery, there were decreased vertical ground reaction forces in weight acceptance and increased forces in late stance. Additional significant changes with ankle-foot orthoses involved increased vertical forces in weight acceptance, and in late stance corresponding to bodyweight (bilateral, from 92% to 98% bodyweight; unilateral, from 94% to 103% bodyweight) postoperatively. INTERPRETATION: Our findings confirmed that surgery affected vertical ground reaction forces to approach more normative patterns. Additional changes with ankle-foot orthoses indicated further improved ability to support bodyweight and decelerate centre of mass in late stance.

Intermediate Dynamic Compression and Decreased Posterior Tilt With Interlocked Pins in Femoral Neck Fixation in Synthetic Bone.

Fixation failure with resulting non-union is the key complication after femoral neck fixation. It can be avoided by permitting dynamic compression and reducing rotation and posterior tilt of the femoral head. To achieve this, a novel implant that features an interlocking plate with three hook-pins (The Hansson Pinloc® System) was developed from the original two hook-pins. Only an enhanced torsional fixation by the implant modification is reported. The purpose was to compare the biomechanical compressive and bending stability of the original and modified implant in femoral neck fixation. To analyze the contribution of both modified components, three individual pins were included, although not in regular use. Forty-eight synthetic femurs with mid-cervical wedge osteotomies were fixated by two pins or identical triangular pin patterns with or without the plate. Eight specimens of each group were loaded cyclically in compression with an inferior wedge to simulate stance and anteroposterior bending with a posterior wedge to imitate sitting down. The clinically relevant stability measurements were stiffness and deformation. Fissure formation defined failure. The novel implant improved bending stability by 30% increased stiffness, 44% reduced deformation, and less frequent posterior neck fissure formation (p < 0.001) while increased compressive stability was only evident with 25% reduced deformation and less frequent inferior neck fissures (p < 0.001). These impacts were mainly mediated by the third pin, while the plate prevented a lateral fissure in compression (p < 0.001). The clinical stability was improved by dynamic compression and decreased posterior tilt by implant modification.

The stabilising effect by a novel cable cerclage configuration in long cephalomedullary nailing of subtrochanteric fractures with a posteromedial wedge.

BACKGROUND: Clinical studies suggest that an adjunctive cerclage in intramedullary nailing of subtrochanteric fractures improves the outcome. Despite this, to what extent various cerclage configurations influences the fixation strength, remains undocumented. We tested the hypothesis that the stability of subtrochanteric fractures with a posteromedial wedge treated with long cephalomedullary nail varies with cerclage configuration. METHODS: 40 composite femurs with a subtrochanteric osteotomy including a posteromedial-wedge were locked by cephalomedullary nailing (T2 recon, Stryker) and divided into 4 groups. In Group-A no cerclage was applied. The Group-B received a lateral tension-band (cerclage cable with crimp, Depuy-Synthes). Without any fixation, the wedge-component was removed in these groups. The Group-C was fixed with a cerclage encircling the wedge-component, while in the Group-D a novel figure-of-8 cerclage stabilised the wedge-component. Each femur was tested quasi-static in a material-testing-machine for stiffness calculation, first horizontally to simulate seated-position and then vertically to simulate standing-position. Finally, cyclic testing was performed in the upright-posture to measure deformation over time. FINDINGS: In Group-D the mean stiffness in the sitting-position was 6.4, 5.8 and 3.1 times higher than the Groups-A, B and C, respectively, and correspondingly 2.0, 2.1 and 1.7 times higher in the standing-position (p < 0.05). Over time, Group-D demonstrated less mean deformation than tension-band (p = 0.05), while the deformation was not significantly different from the other groups. INTERPRETATION: Additional use of cerclage enhances the stability of intramedullary nailed subtrochanteric fractures, and use of the figure-of-8 cerclage configuration, compressing the entire posteromedial-buttress, is the superior technique.

High correlation between mechanical properties and bone mineral parameters in embalmed femurs after long-term storage.

BACKGROUND: Fresh frozen human femurs are considered "the gold standard" in biomechanical studies of hip fractures, resembling the in vivo situation mostly. A more readily available alternative is formalin embalmed femurs. However, to which extent formalin affects key features of bone; its mechanical properties, bone mineral content and their mutual relationship over time, remains unknown. Accordingly, we measured the mineral parameters and related them to the mechanical properties of formalin fixed femurs after long-term storage. METHODS: 36 paired femurs from human donors, fixed in formalin and stored for a mean period of 4.6 (3.5-6) years. Quantitative CT was performed to measure the bone mineral density and mass at the mainly cortical mid shaft and the center of the mainly cancellous condyles. Each pair was subjected to local tests by three-point bending and screw pullout of the shaft and lateral punch and metaphyseal cube compression of the condyles. FINDINGS: Neither mechanical nor bone mineral data were significantly correlated to storage time. Well-known associations for bone parameters with age and gender were retrieved. Maximum force of the cortical bone tests was highly correlated to the diaphyseal bone mass; (r = 0.80-0.87, p = 0.01), while maximum force of the cancellous bone tests correlated well to the density of the condylar bone; (r = 0.70, p = 0.01). INTERPRETATION: Our results indicate that mechanical and bone mineral data and their mutual relationship are conserved in formalin fixed femurs even after long-term storage. Formalin fixed femurs may serve as an alternative to fresh frozen femurs in biomechanical testing.

Increased torsional stability by a novel femoral neck locking plate. The role of plate design and pin configuration in a synthetic bone block model.

BACKGROUND: In undisplaced femoral neck fractures, internal fixation remains the main treatment, with mechanical failure as a frequent complication. As torsional stable fixation promotes femoral neck fracture healing, the Hansson Pinloc® System with a plate interlocking pins, was developed from the original hook pins. Since its effect on torsional stability is undocumented, the novel implant was compared with the original configurations. METHODS: Forty-two proximal femur models custom made of two blocks of polyurethane foam were tested. The medial block simulated the cancellous head, while the lateral was laminated with a glass fiber filled epoxy sheet simulating trochanteric cortical bone. Two hollow metal cylinders with a circumferential ball bearing in between mimicked the neck, with a perpendicular fracture in the middle. Fractures were fixated by two or three independent pins or by five configurations involving the interlocking plate (two pins with an optional peg in a small plate, or three pins in a small, medium or large plate). Six torsional tests were performed on each configuration to calculate torsional stiffness, torque at failure and failure energy. FINDINGS: The novel configurations improved parameters up to an average of 12.0 (stiffness), 19.3 (torque) and 19.9 (energy) times higher than the original two pins (P < 0.001). The plate, its size and its triangular configuration improved all parameters (P = 0.03), the plate being most effective, also preventing permanent failure (P < 0.001). INTERPRETATION: The novel plate design with its pin configuration enhanced torsional stability. To reveal clinical relevance a clinical study is planned.

Negative effect of zoledronic acid on tendon-to-bone healing.

Background and purpose - Outcome after ligament reconstruction or tendon repair depends on secure tendon-to-bone healing. Increased osteoclastic activity resulting in local bone loss may contribute to delayed healing of the tendon-bone interface. The objective of this study was to evaluate the effect of the bisphosphonate zoledronic acid (ZA) on tendon-to-bone healing. Methods - Wistar rats (n = 92) had their right Achilles tendon cut proximally, pulled through a bone tunnel in the distal tibia and sutured anteriorly. After 1 week animals were randomized to receive a single dose of ZA (0.1 mg/kg IV) or control. Healing was evaluated at 3 and 6 weeks by mechanical testing, dual-energy X-ray absorptiometry and histology including immunohistochemical staining of osteoclasts. Results - ZA treatment resulted in 19% (95% CI 5-33%) lower pullout strength and 43% (95% CI 14-72%) lower stiffness of the tendon-bone interface, compared with control (2-way ANOVA; p = 0.009, p = 0.007). Administration of ZA did not affect bone mineral density (BMD) or bone mineral content (BMC). Histological analyses did not reveal differences in callus formation or osteoclasts between the study groups. Interpretation - ZA reduced pullout strength and stiffness of the tendon-bone interface. The study does not provide support for ZA as adjuvant treatment in tendon-to-bone healing.