The purpose of this study was to describe the anatomical distribution and incidence of fatigue injuries of the femur in physically-active young adults, based upon MRI studies. During a period of 70 months, 1857 patients with exercise-induced pain in the femur underwent MRI of the pelvis, hips, femora, and/or knees. Of these, 170 patients had a total of 185 fatigue injuries, giving an incidence of 199 per 100 000 person-years. Bilateral injuries occurred in 9% of patients. The three most common sites affected were the femoral neck (50%), the condylar area (24%) and the proximal shaft (18%). A fatigue reaction was seen in 57%, and a fracture line in 22%. There was a statistical correlation between the severity of the fatigue injury and the duration of pain (p = 0.001). The location of the pain was normally at the site of the fatigue injury. Fatigue injuries of the femur appear to be relatively common in physically-active patients

Objectives. Screw plugs have been reported to increase the fatigue strength of stainless steel locking plates. The objective of this study was to examine and compare this effect between stainless steel and titanium locking plates. Methods. Custom-designed locking plates with identical structures were fabricated from stainless steel and a titanium alloy. Three types of plates were compared: type I unplugged plates; type II plugged plates with a 4 Nm torque; and type III plugged plates with a 12 Nm torque. The stiffness, yield strength, and fatigue strength of the plates were investigated through a four-point bending test. Failure analyses were performed subsequently. Results. For stainless steel, type II and type III plates had significantly higher fatigue strength than type I plates. For titanium, there were no significant differences between the fatigue strengths of the three types of plates. Failure analyses showed local plastic deformations at the threads of screw plugs in type II and type III stainless steel plates but not in titanium plates. Conclusion. The screw plugs could increase the fatigue strength of stainless steel plates but not of titanium plates. Therefore, leaving screw holes open around fracture sites is recommended in titanium plates. Cite this article: L-W. Hung, C-K. Chao, J-R. Huang, J. Lin. Screw head plugs increase the fatigue strength of stainless steel, but not of titanium, locking plates. Bone Joint Res 2018;7:629–635. DOI: 10.1302/2046-3758.712.BJR-2018-0083.R1

Aims. To determine whether half-threaded screw holes in a new titanium locking plate design can substantially decrease the notch effects of the threads and increase the plate fatigue life. Methods. Three types (I to III) of titanium locking plates were fabricated to simulate plates used in the femur, tibia, and forearm. Two copies of each were fabricated using full- and half-threaded screw holes (called A and B, respectively). The mechanical strengths of the plates were evaluated according to the American Society for Testing and Materials (ASTM) F382-14, and the screw stability was assessed by measuring the screw removal torque and bending strength. Results. The B plates had fatigue lives 11- to 16-times higher than those of the A plates. Before cyclic loading, the screw removal torques were all higher than the insertion torques. However, after cyclic loading, the removal torques were similar to or slightly lower than the insertion torques (0% to 17.3%), although those of the B plates were higher than those of the A plates for all except the type III plates (101%, 109.8%, and 93.8% for types I, II, and III, respectively). The bending strengths of the screws were not significantly different between the A and B plates for any of the types. Conclusion. Removing half of the threads from the screw holes markedly increased the fatigue life of the locking plates while preserving the tightness of the screw heads and the bending strength of the locking screws. However, future work is necessary to determine the relationship between the notch sensitivity properties and titanium plate design. Cite this article: Bone Joint Res 2020;9(10):645–652

Aims. Due to their radiolucency and favourable mechanical properties, carbon fibre nails may be a preferable alternative to titanium nails for oncology patients. We aim to compare the surgical characteristics and short-term results of patients who underwent intramedullary fixation with either a titanium or carbon fibre nail for pathological long-bone fracture. Methods. This single tertiary-institutional, retrospectively matched case-control study included 72 patients who underwent prophylactic or therapeutic fixation for pathological fracture of the humerus, femur, or tibia with either a titanium (control group, n = 36) or carbon fibre (case group, n = 36) intramedullary nail between 2016 to 2020. Patients were excluded if intramedullary fixation was combined with any other surgical procedure/fixation method. Outcomes included operating time, blood loss, fluoroscopic time, and complications. Fisher’s exact test and Mann-Whitney U test were used for categorical and continuous outcomes, respectively. Results. Patients receiving carbon nails as compared to those receiving titanium nails had higher blood loss (median 150 ml (interquartile range (IQR) 100 to 250) vs 100 ml (IQR 50 to 150); p = 0.042) and longer fluoroscopic time (median 150 seconds (IQR 114 to 182) vs 94 seconds (IQR 58 to 124); p = 0.001). Implant complications occurred in seven patients (19%) in the titanium group versus one patient (3%) in the carbon fibre group (p = 0.055). There were no notable differences between groups with regard to operating time, surgical wound infection, or survival. Conclusion. This pilot study demonstrates a non-inferior surgical and short-term clinical profile supporting further consideration of carbon fibre nails for pathological fracture fixation in orthopaedic oncology patients. Given enhanced accommodation of imaging methods important for oncological surveillance and radiation therapy planning, as well as high tolerances to fatigue stress, carbon fibre implants possess important oncological advantages over titanium implants that merit further prospective investigation. Level of evidence: III, Retrospective study. Cite this article: Bone Jt Open 2022;3(8):648–655

1. A hope expressed in 1940, that further cases of spontaneous fracture of the lowest third of the apparently normal fibula would be described, has been fulfilled. The literature is here reviewed. Five further personal cases are added. 2. The clinical and radiographic features, diagnosis, treatment and results are considered in the light of the information so far available. Special note is made of misleading freedom of ankle and tarsal movements and the occasional absence of tenderness. 3. It is established that fractures of the lowest third occur particularly in two groups of subjects: 1) young male runners and skaters; 2) active and hard-pressed women of middle age and over. 4. In male runners and skaters the fracture usually occurs through slender, mainly cortical bone, two inches or more above the tip of the lateral malleolus; in middle-aged women the fracture is usually distal to the interosseous ligament through thicker, mainly cancellous bone, one and a half inches from the tip of the lateral malleolus. 5. The most convenient name for both groups of fractures in the lowest third is low fatigue fracture of the fibula. 6. A review of the literature of fatigue fracture of the uppermost third of the fibula shows that it is very often precipitated by jumping. The most convenient name for it is high fatigue fracture of the fibula. 7. Like all clinical classifications this distinction between low and high fractures has exceptions (a low fracture of one fibula in a runner was followed later by a high fracture of the other; most military fractures were high, but a few may have occurred at other levels). 8. Fatigue fracture of the fibula, high or low, may be bilateral. 9. A fracture similarly situated to the high fatigue fracture of the fibula has been frequent in parachute schools. It is a speculative possibility that military and parachutist fractures of the upper third of the fibula indicate the link between true fatigue fractures (as exemplified by march fractures with minimal trauma often repeated) and purely traumatic fractures (with adequate trauma applied once only)

The incidence and long-term outcome of undisplaced fatigue fractures of the femoral neck treated conservatively were examined in Finnish military conscripts between 1970 and 1990. From 106 cases identified, 66 patients with 70 fractures were followed for a mean of 18.3 years (11 to 32). The original medical records and radiographs were studied and physical and radiological follow-up data analysed for evidence of risk factors for this injury. The development of avascular necrosis and osteoarthritis was determined from the follow-up radiographs and MR scans. The impact of new military instructions on the management of hip-related pain was assessed following their introduction in 1986. The preventive regimen (1986) improved awareness and increased the detected incidence from 13.2 per 100 000 service-years (1970 to 1986) to 53.2 per 100 000 (1987 to 1990). No patient developed displacement of the fracture or avascular necrosis of the femoral head, or suffered from adverse complications. No differences were found in MRI-measured hip joint spaces at final follow-up. The mean Harris Hip Score was 97 (70 to 100) and the Visual Analogue Scale 5.85 mm (0 to 44). Non-operative treatment, including avoidance of or reduced weight-bearing, gave favourable short- and long-term outcomes. Undisplaced fatigue fractures of the femoral neck neither predispose to avascular necrosis nor the subsequent development of osteoarthritis of the hip

Filling the empty holes in peri-articular locking plates may improve the fatigue strength of the fixation. The purpose of this in vitro study was to investigate the effect of plugging the unused holes on the fatigue life of peri-articular distal femoral plates used to fix a comminuted supracondylar fracture model. A locking/compression plate was applied to 33 synthetic femurs and then a 6 cm metaphyseal defect was created (AO Type 33-A3). The specimens were then divided into three groups: unplugged, plugged with locking screw only and fully plugged holes. They were then tested using a stepwise or run-out fatigue protocol, each applying cyclic physiological multiaxial loads. All specimens in the stepwise group failed at the 770 N load level. The mean number of cycles to failure for the stepwise specimen was 25 500 cycles (. sd. 1500), 28 800 cycles (. sd.  6300), and 26 400 cycles (. sd. 2300) cycles for the unplugged, screw only and fully plugged configurations, respectively (p = 0.16). The mean number of cycles to failure for the run-out specimens was 42 800 cycles (. sd. 10 700), 36 000 cycles (. sd. 7200), and 36 600 cycles (. sd.  10 000) for the unplugged, screw only and fully plugged configurations, respectively (p = 0.50). There were also no differences in axial or torsional stiffness between the constructs. The failures were through the screw holes at the level of comminution. In conclusion, filling the empty combination locking/compression holes in peri-articular distal femur locking plates at the level of supracondylar comminution does not increase the fatigue life of the fixation in a comminuted supracondylar femoral fracture model (AO 33-A3) with a 6 cm gap

We investigated a new intramedullary locking nail that allows the distal interlocking screws to be locked to the nail. We compared fixation using this new implant with fixation using either a conventional nail or a locking plate in a laboratory simulation of an osteoporotic fracture of the distal femur. A total of 15 human cadaver femora were used to simulate an AO 33-A3 fracture pattern. Paired specimens compared fixation using either a locking or non-locking retrograde nail, and using either a locking retrograde nail or a locking plate. The constructs underwent cyclical loading to simulate single-leg stance up to 125 000 cycles. Axial and torsional stiffness and displacement, cycles to failure and modes of failure were recorded for each specimen. When compared with locking plate constructs, locking nail constructs had significantly longer mean fatigue life (75 800 cycles (. sd. 33 900) vs 12 800 cycles (. sd. 6100); p = 0.007) and mean axial stiffness (220 N/mm (. sd. 80) vs 70 N/mm (. sd. 18); p = 0.005), but lower mean torsional stiffness (2.5 Nm/° (. sd. 0.9) vs 5.1 Nm/° (. sd. 1.5); p = 0.008). In addition, in the nail group the mode of failure was either cut-out of the distal screws or breakage of nails, and in the locking plate group breakage of the plate was always the mode of failure. Locking nail constructs had significantly longer mean fatigue life than non-locking nail constructs (78 900 cycles (. sd. 25 600) vs 52 400 cycles (. sd. 22 500); p = 0.04). The new locking retrograde femoral nail showed better stiffness and fatigue life than locking plates, and superior fatigue life to non-locking nails, which may be advantageous in elderly patients. Cite this article: Bone Joint J 2014;96-B:114–21

1. The femoral head has been examined in specimens taken from cadavers, patients suffering subcapital fracture of the femoral neck and patients undergoing total replacement arthroplasty for osteoarthrosis and rheumatoid arthritis. 2. Lesions have been seen, some of which appear to be uniting fatigue fractures of individual trabeculae. 3. It is suggested that excessive cyclical loading, sometimes leading to fatigue fractures, may represent a fundamental pathological process of general importance in the evolution of certain skeletal and articular diseases

1. Senile subcapital fractures in osteoporotic patients are due to fatigue, not to the impact of a fall, since they are preceded by the local accumulation of isolated trabecular fatigue fractures. 2. One pathological significance of the isolated trabecular fractures described by Todd, Freeman and Pirie (1972) has been demonstrated

1. A defect of the middle of one tibial crest is described in young healthy ballet dancers. 2. The clinical and radiological characteristics have been studied in four cases, and the histological appearances in two. 3. The defect is concluded to be an incomplete fatigue fracture—a fatigue infraction. 4. A fifth, uncertain, case has been added tentatively, as presenting a possible serious complication, namely acute fracture from muscle action. 5. The diagnosis, treatment and prognosis are mentioned, with emphasis on the importance of adequate clinical and radiological examination in cases of obscure mid-tibial pain, tenderness or swelling

1. Thirty-seven specimens of the proximal third of the human femur were subjected to cyclically varying loads applied in a physiological direction to the femoral head, having maximum values of from four to thirteen times body weight. 2. Ten of these specimens sustained subcapital fractures of the femoral neck after numbers of cycles of loading varying from 123 to 8,193. 3. The maximum value of cyclic load needed to give fatigue fracture after 10,000 or fewer cycles was found to vary from about twelve times the body weight at ages twenty to fifty to about five times the body weight at age seventy or more. 4. In youth and in middle age the load levels mentioned above are greater than those encountered in normal living, but are comparable to those which may be applied to the femoral head during activities known to produce "fatigue" fractures clinically in young adults. 5. In the elderly the load levels mentioned above are within the range that can be applied in normal living. It is inferred that some femoral neck fractures in the elderly may be fatigue fractures caused by the cyclic loading of normal walking

1. Two cases of fatigue fracture of the ulna are reported. 2. Three cases previously reported are reviewed and a striking similarity with one of the present cases is noted. 3. In all cases the mechanism of injury appears to have been the same

1. Three cases are reported of ischaemic necrosis of the anterior tibial muscles which were not due to injury. In two, ischaemia was the result of strenuous or unaccustomed exercise in young adults; in the third it was an incident in a systemic disturbance. All three cases were probably the result of spasm of a large segment of the anterior tibial artery. 2. The clinical features during the first few hours resemble those of tenosynovitis of the tibialis anterior; and after twelve to twenty-four hours those of cellulitis of the leg. Later there is "drop foot" due to muscle weakness, contracture limiting plantar-flexion movement, and woody hardness of the muscles in the middle third. 3. The morbid histology is similar to that of Volkmann's ischaemic contracture. 4. The possible explanations—primary arterial disease, arterial occlusion by pressure of the interosseous membrane, occlusion by tension within the fascial space, intraluminary occlusion by embolism or thrombosis, and fatigue arterial spasm, are discussed. 5. The vascular pattern of the anterior tibial muscles has been studied by experimental injections in cadavers. 6. It is concluded that the most likely cause is spasm of the anterior tibial artery due to muscle fatigue, aggravated by increased tension within the anterior fascial compartment due to reaction after strenuous exercise. 7. Treatment is outlined. Exploration of the anterior tibial artery within the first twelve hours is warranted, but late exploration may be dangerous. 8. Although not previously recognised, evidence is shown that regeneration of necrotic muscle is possible in the human being

Forty-one cadaveric lumbar intervertebral joints from 18 spines were flexed and fatigue loaded to simulate a vigorous day's activity. The joints were then bisected and the discs examined. Twenty-three out of 41 of the discs showed distortions in the lamellae of the annulus fibrosus and, in a few of these, complete radial fissures were found in the posterior annulus

1. Five patients with seven fatigue fractures of the lower third of the tibia are described; two had bilateral fractures. There is a striking similarity in the site and appearance of these fractures. 2. All occurred in middle-aged or elderly people without a history of unusual activity or illness. 3. The fractures are so nearly identical as to constitute an entity which, as far as we are aware, has not been described before

1. A case is described of fatigue fractures occurring in the lowest thirds of the right tibia and fibula simultaneously. 2. The fibular fracture was a runner's fracture. 3. The tibial fracture was ascribed to the application of a below-knee walking plaster to treat the fibular lesion. 4. Both fractures were slow in uniting. 5. The fractures occurred in a rapidly growing youth but no clinical evidence of an endocrine dysfunction was found

The causes of mechanical failure of five noncemented porous-coated components were studied. There were two cobalt-chromium alloy and three titanium alloy implants which fractured after 12 to 48 months. The implants included one acetabular component, and one femoral condylar, one patellar and two tibial components. Examination of the fractured surfaces revealed fatigue to be the mechanism of failure in all cases. The porous coating and the processes required for its fabrication had resulted in weakening and reduction of substrate thickness. Additional factors were stress concentration due to limited, localised bone ingrowth, and some features of the design of the implants