Biopsies of lumbar multifidus muscles were obtained at operation on seventeen patients aged from fifteen to fifty-eight with lumbar spinal derangement, and further material was taken from the cadavers of three subjects aged from nineteen to fifty-one. Sections were prepared to show the presence of ATPase activity, so distinguishing Fast from Slow types of muscle fibre. The normal mosaic pattern arising from the intermingling of fibres from Fast and Slow motor units was seen in sections from cadaveric material and from many of the biopsies. With age and limited lumbar flexibility, the Fast fibres became relatively smaller but with increasing variation in size, suggesting a reduced capacity for phasic activity. The presence of positive root signs was associated with a greater proportion of Slow fibres, and in some patients with the occurrence of atrophied Fast fibres, giving rise to differences in the populations of the two fibres in neighbouring fascicles. The results suggest that multifidus adopts an increasingly postural role with advancing age and with disabling lesions of the lumbar spine

The understanding of rotational alignment of the distal femur is essential in total knee replacement to ensure that there is correct placement of the femoral component. Many reference axes have been described, but there is still disagreement about their value and mutual angular relationship. Our aim was to validate a geometrically-defined reference axis against which the surface-derived axes could be compared in the axial plane. A total of 12 cadaver specimens underwent CT after rigid fixation of optical tracking devices to the femur and the tibia. Three-dimensional reconstructions were made to determine the anatomical surface points and geometrical references. The spatial relationships between the femur and tibia in full extension and in 90° of flexion were examined by an optical infrared tracking system. After co-ordinate transformation of the described anatomical points and geometrical references, the projection of the relevant axes in the axial plane of the femur were mathematically achieved. Inter- and intra-observer variability in the three-dimensional CT reconstructions revealed angular errors ranging from 0.16° to 1.15° for all axes except for the trochlear axis which had an interobserver error of 2°. With the knees in full extension, the femoral transverse axis, connecting the centres of the best matching spheres of the femoral condyles, almost coincided with the tibial transverse axis (mean difference −0.8°, . sd. 2.05). At 90° of flexion, this femoral transverse axis was orthogonal to the tibial mechanical axis (mean difference −0.77°, . sd. 4.08). Of all the surface-derived axes, the surgical transepicondylar axis had the closest relationship to the femoral transverse axis after projection on to the axial plane of the femur (mean difference 0.21°, . sd. 1.77). The posterior condylar line was the most consistent axis (range −2.96° to −0.28°, . sd. 0.77) and the trochlear anteroposterior axis the least consistent axis (range −10.62° to +11.67°, . sd. 6.12). The orientation of both the posterior condylar line and the trochlear anteroposterior axis (p = 0.001) showed a trend towards internal rotation with valgus coronal alignment

Impacted morsellised allografts have been used successfully to address the problem of poor bone stock in revision surgery. However, there are concerns about the transmission of pathogens, the high cost and the shortage of supply of donor bone. Bone-graft extenders, such as tricalcium phosphate (TCP) and hydroxyapatite (HA), have been developed to minimise the use of donor bone. In a human cadaver model we have evaluated the surgical and mechanical feasibility of a TCP/HA bone-graft extender during impaction grafting revision surgery. A TCP/HA allograft mix increased the risk of producing a fissure in the femur during the impaction procedure, but provided a higher initial mechanical stability when compared with bone graft alone. The implications of the use of this type of graft extender in impaction grafting revision surgery are discussed

Aims

The gluteus minimus (GMin) and gluteus medius (GMed) have unique structural and functional segments that may be affected to varying degrees, by end-stage osteoarthritis (OA) and normal ageing. We used data from patients with end-stage OA and matched healthy controls to 1) quantify the atrophy of the GMin and GMed in the two groups and 2) describe the distinct patterns of the fatty infiltration in the different segments of the GMin and GMed in the two groups.

Aims

Periprosthetic fractures (PPFs) around cemented taper-slip femoral prostheses often result in a femoral component that is loose at the prosthesis-cement interface, but where the cement-bone interface remains well-fixed and bone stock is good. We aim to understand how best to classify and manage these fractures by using a modification of the Vancouver classification.

The medial displacement osteotomy of Chiari has an established place in the management of older children and adults with severe hip dysplasia. The results claimed for the operation are, however, variable. There have also been reports of sciatic nerve lesions. In this study ten cadavers were operated upon. Chiari osteotomy was performed upon five, and five acted as controls. The hemipelvis was removed from each cadaver; each specimen was deep-frozen and sectioned transversely. The distance of the sciatic nerve from the nearest bony point was measured in each section and the results were recorded graphically. A further radiographic and photographic study was performed to determine whether apparent displacement at the osteotomy might be misleading. The conclusion was drawn that the sciatic nerve is angulated at the osteotomy and further endangered by the risk of bone splintering at the sciatic notch. The radiographic study suggested that some poor clinical results may be explained by a radiological artefact, because there is a tendency for the osteotomy to hinge posteriorly at the sciatic notch opening anteriorly like a book. Radiographs may suggest excellent medial displacement whereas in fact the femoral head is very poorly covered

We undertook this study to determine the minimum amount of coronoid necessary to stabilise an otherwise intact elbow joint. Regan–Morrey types II and III, plus medial and lateral oblique coronoid fractures, collectively termed type IV fractures, were simulated in nine fresh cadavers. An electromagnetic tracking system defined the three-dimensional stability of the ulna relative to the humerus. The coronoid surface area accounts for 59% of the anterior articulation. Alteration in valgus, internal and external rotation occurred only with a type III coronoid fracture, accounting for 68% of the coronoid and 40% of the entire articular surface. A type II fracture removed 42% of the coronoid articulation and 25% of the entire articular surface but was associated with valgus and external rotational changes only when the radial head was removed, thereby removing 67% of the articular surface. We conclude that all type III fractures, as defined here, are unstable, even with intact ligaments and a radial head. However, a type II deficiency is stable unless the radial head is removed. Our study suggests that isolated medial-oblique or lateral-oblique fractures, and even a type II fracture with intact ligaments and a functional radial head, can be clinically stable, which is consistent with clinical observation.

The tensile strength of the medial patellofemoral ligament (MPFL), and of surgical procedures which reconstitute it, are unknown. Ten fresh cadaver knees were prepared by isolating the patella, leaving only the MPFL as its attachment to the medial femoral condyle. The MPFL was either repaired by using a Kessler suture or reconstructed using either bone anchors or one of two tendon grafting techniques. The tensile strength and the displacement to peak force of the MPFL were then measured using an Instron materials-testing machine. The MPFL was found to have a mean tensile strength of 208 N (SD 90) at 26 mm (SD 7) of displacement. The strengths of the other techniques were: sutures alone, 37 N (SD 27); bone anchors plus sutures, 142 N (SD 39); blind-tunnel tendon graft, 126 N (SD 21); and through-tunnel tendon graft, 195 N (SD 66). The last was not significantly weaker than the MPFL itself

The risk of articular penetration during tibial nailing is well known, but the incidence of unrecognised damage to joint cartilage has not been described. We have identified this complication in the treatment of tibial fractures, described the anatomical structures at risk and examined the most appropriate site of entry for tibial nailing in relation to the shape of the bone, the design of the nail and the surgical approach. We studied the relationship between the intra-articular structures of the knee and the entry point used for nailing in 54 tibiae from cadavers. The results showed that the safe zone in some bones is smaller than the size of standard reamers and the proximal part of some nails. The structures at risk are the anterior horns of the medial and lateral menisci, the anterior part of the medial and lateral plateaux and the ligamentum transversum. This was confirmed by observations made after nailing 12 pairs of cadaver knees. A retrospective radiological analysis of 30 patients who had undergone tibial nailing identified eight at risk according to the entry point and the size of the nail. Unrecognised articular penetration and damage during surgery were confirmed in four. Although intramedullary nailing has been shown to be a successful method for treating fractures of the tibia, one of the most common problems after bony union is pain in the knee. Unrecognised intra-articular injury of the knee may be one cause of this

When performing the Scandinavian Total Ankle Replacement (STAR), the positioning of the talar component and the selection of mobile-bearing thickness are critical. A biomechanical experiment was undertaken to establish the effects of these variables on the range of movement (ROM) of the ankle. Six cadaver ankles containing a specially-modified STAR prosthesis were subjected to ROM determination, under weight-bearing conditions, while monitoring the strain in the peri-ankle ligaments. Each specimen was tested with the talar component positions in neutral, as well as 3 and 6 mm of anterior and posterior displacement. The sequence was repeated with an anatomical bearing thickness, as well as at 2 mm reduced and increased thicknesses. The movement limits were defined as 10% strain in any ligament, bearing lift-off from the talar component or limitations of the hardware. Both anterior talar component displacement and bearing thickness reduction caused a decrease in plantar flexion, which was associated with bearing lift-off. With increased bearing thickness, posterior displacement of the talar component decreased plantar flexion, whereas anterior displacement decreased dorsiflexion

Aims

Surgical treatment of hip fracture is challenging; the bone is porotic and fixation failure can be catastrophic. Novel implants are available which may yield superior clinical outcomes. This study compared the clinical effectiveness of the novel X-Bolt Hip System (XHS) with the sliding hip screw (SHS) for the treatment of fragility hip fractures.

The aim of this study was to validate the use of three models of fracture fixation in the assessment of technical skills. We recruited 21 subjects (six experts, seven intermediates, and eight novices) to perform three procedures: application of a dynamic compression plate on a cadaver porcine model, insertion of an unreamed tibial intramedullary nail, and application of a forearm external fixator, both on synthetic bone models. The primary outcome measures were the Objective Structural Assessment of technical skills global rating scale on video recordings of the procedures which were scored by two independent expert observers, and the hand movements of the surgeons which were analysed using the Imperial College Surgical Assessment Device. The video scores were significantly different for the three groups in all three procedures (p < 0.05), with excellent inter-rater reliability (α = 0.88). The novice and intermediate groups specifically were significantly different in their performance with dynamic compression plate and intramedullary nails (p < 0.05). Movement analysis distinguished between the three groups in the dynamic compression plate model, but a ceiling effect was demonstrated in the intramedullary nail and external fixator procedures, where intermediates and experts performed to comparable standards (p > 0.6). A total of 85% (18 of 21) of the subjects found the dynamic compression model and 57% (12 of 21) found all the models acceptable tools of assessment. This study has validated a low-cost, high-fidelity porcine dynamic compression plate model using video rating scores for skills assessment and movement analysis. It has also demonstrated that Synbone models for the application of and intramedullary nail and an external fixator are less sensitive and should be improved for further assessment of surgical skills in trauma. The availability of valid objective tools of assessment of surgical skills allows further studies into improving methods of training

Aims

The extensive variation in axial rotation of tibial components can lead to coronal plane malalignment. We analyzed the change in coronal alignment induced by tray malrotation.

Objectives. Cement augmentation of pedicle screws could be used to improve screw stability, especially in osteoporotic vertebrae. However, little is known concerning the influence of different screw types and amount of cement applied. Therefore, the aim of this biomechanical in vitro study was to evaluate the effect of cement augmentation on the screw pull-out force in osteoporotic vertebrae, comparing different pedicle screws (solid and fenestrated) and cement volumes (0 mL, 1 mL or 3 mL). Materials and Methods. A total of 54 osteoporotic human cadaver thoracic and lumbar vertebrae were instrumented with pedicle screws (uncemented, solid cemented or fenestrated cemented) and augmented with high-viscosity PMMA cement (0 mL, 1 mL or 3 mL). The insertion torque and bone mineral density were determined. Radiographs and CT scans were undertaken to evaluate cement distribution and cement leakage. Pull-out testing was performed with a material testing machine to measure failure load and stiffness. The paired t-test was used to compare the two screws within each vertebra. Results. Mean failure load was significantly greater for fenestrated cemented screws (+622 N; p ⩽ 0.001) and solid cemented screws (+460 N; p ⩽ 0.001) than for uncemented screws. There was no significant difference between the solid and fenestrated cemented screws (p = 0.5). In the lower thoracic vertebrae, 1 mL cement was enough to significantly increase failure load, while 3 mL led to further significant improvement in the upper thoracic, lower thoracic and lumbar regions. Conclusion. Conventional, solid pedicle screws augmented with high-viscosity cement provided comparable screw stability in pull-out testing to that of sophisticated and more expensive fenestrated screws. In terms of cement volume, we recommend the use of at least 1 mL in the thoracic and 3 mL in the lumbar spine. Cite this article: C. I. Leichtle, A. Lorenz, S. Rothstock, J. Happel, F. Walter, T. Shiozawa, U. G. Leichtle. Pull-out strength of cemented solid versus fenestrated pedicle screws in osteoporotic vertebrae. Bone Joint Res 2016;5:419–426

Aims

Femoroacetabular impingement (FAI) is a potential cause of hip osteoarthritis (OA). The purpose of this study was to investigate the expression profile of matrix metalloproteinases (MMPs) in the labral tissue with FAI pathology.

Aims

The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA).

Aims

Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation.

Aims

The aim of this study was to explore why some calcar screws are malpositioned when a proximal humeral fracture is treated by internal fixation with a locking plate, and to identify risk factors for this phenomenon. Some suggestions can be made of ways to avoid this error.

Aims

The aim of this systematic review and meta-analysis is to evaluate differences in functional outcomes and complications between single- (SI) and double-incision (DI) techniques for the treatment of distal biceps tendon rupture.