Evaluation of the Effects of Holes of Various Sizes on Fracture Rates in Sheep Femurs

Abstract

SummaryDefects in long bones are known to lead to increased risk of pathologic fracture. Holes weaken bones and increase the risk of fracture during bending, especially on exposure to torsional forces. Here, we investigated the effect of holes of varying numbers and sizes drilled into sheep femur bones on the resistance of the bone to torsional forces. Ninety-six fresh sheep femur bones were allocated to 8 groups, which were further subdivided into 4 groups of 3 bones each. In each group, 1 to 4 holes ranging from 2 to 5.5 mm were drilled into the femurs, and the bones were subjected to a rotation test. Forces that caused fractures and the force curves were measured and recorded. The effect of the number and size of the holes drilled in the femurs on the occurrence of fractures was compared using two-way analysis of variance, and Tukey's multiple comparison test was used for multiple comparisons. P<0.05 was considered statistically significant. We found that the resistance of a bone to torsional forces decreased significantly with increase in the number and size of the drilled holes (P<0.001). The rate of fractures increased as the number and sizes of the holes increased. The resistance of the bones to torsional forces decreased as the number of holes increased. We showed that the size of a defect in a bone is extremely important for torsional resistance and is, in fact, more important than the number of defects. Keywords: Fracture, Rotational forces, Bone, Femur, Sheep Koyun Femurlarında Çeşitli Boyutlardaki Deliklerin Kırık Oranları Üzerine Etkilerinin Değerlendirilmesi ÖzetUzun kemiklerdeki defektlerin patololojik kırığa neden olduğu bilinmektedir. Delikler özellikle torsiyonel güçlere maruz kalınca bükülme esnasında kemiği zayıflatır ve kırık riskini artırır. Buradaki çalışmamızda biz koyun femur kemiklerinde drille delinmiş çeşitli sayı ve boyutlardaki deliklerin etkilerini araştırdık. 96 tane taze koyun kemiği her biri ilaveten 3 kemiği içeren 4'lü alt gruplara bölünerek 8 gruba ayrıldı. Her bir grubta 2 mm'den 5.5 mm'ye kadar değişen 1'den 4'e kadar delikler femurlar delinerek açıldı ve kemikler rotasyon testine tabi tutuldular. Kırığa neden olan kuvvetler ve kuvvet eğrileri ölçüldü ve kayıt edildi. Delik açılan femurlarda kırık oluşturan deliklerin boyutları ve sayısının etkisi iki yönlü varyans analizi ve Tukey'in çoklu karşılaştırma testi ile mukayese edildi. P<0.05 istatistiksel olarak anlamlı bulundu. Dril ile delinmiş deliklerin boyut ve sayısında artma ile birlikte kemiğin torsiyonel kuvvetlere karşı direncinin önemli derecede azaldığını bulduk (P<0.001). Kırık oranı deliklerin sayısı ve boyutu arttıkça artmaktadır. Torsiyonel kuvvetlere karşı kemiğin direnci deliklerin sayısı arttıkça azalmaktadır. Biz bir kemik defektinin boyutunun torsiyonel direnç için oldukça önemli olduğunu ve gerçekte de defektlerin sayısının boyutuna göre daha etkili olduğunu gösterdik.

Removal of forearm plate leads to a high risk of refracture: decision regarding implant removal after fixation of the forearm and analysis of risk factors of refracture

“…They found that the torsional strength and bending strength decreased to 60 % in bones with one screw hole as compared with intact bones. Olcay et al [19] also reported that the bone strength decreased in relation to the diameter of the screw hole. These results support our findings, as only 2 of 58 bones had bone defects and both were refractured after implant removal.…”

Influence of Screw-Hole Defect Size on the Biomechanical Properties of Feline Femora in an Ex Vivo Model

“…This effect is highlighted in mechanical work involving ovine femora with varying numbers and sizes of drill-holes. 18 Torsional resistance significantly decreased with increasing number of defects, albeit defect size was still noted to be the most important factor influencing failure strength. 18 Flexural properties of intact feline femora measured in this study are consistent with previously reported values.…”

“…In contrast to our screw-hole model, previous studies used bicortical drill-holes for the experimental defect. 5,6,8,[16][17][18] Area and polar moment of inertia are geometric functions of stiffness based on the object's cross-sectional profile to resist bending and torsional deformation respectively. Histomorphometry of 4 mm screw-holes in ovine pedicles showed between 14.2 and 37.4 µm 2 of bone were left within the screw-thread interface, depending on pilot hole diameter.…”

“…However, study designs directly evaluating screw-hole defects are scant, 15 with similar work across species employing bicortical drillholes as the defect model to be challenged under quasi-static loading. 5,6,8,[16][17][18] For screw-and drill-holes of the same size, the former is created with a pilot hole marginally larger than the screw core diameter and finished via hand-tapping or self-tapping screw insertion of the intended size. 2 Hence, drill-hole defects are not created identical to same-sized screw-holes left in situ following screw removal.…”

Structural and Histopathologic Changes of Calf Tibial Bones Subjected to Various Drilling Processes

“…During orthopaedic operations, drilling is the common process and heat generated in bone is inevitable 1 . The heat is a serious clinical concern because of its potential to cause bone damage and bad osseointegration in the implantation processes.…”