In order to determine whether an allogeneic tendon could be used to replace an extra-articular ligament, the right medial collateral ligament from 11 adult dogs was replaced with a fresh-frozen allogeneic patellar tendon. At each of 3, 6, 15, 30 and 52 weeks postoperatively, one dog was killed for micro-angiographical and histological studies; at 52 weeks the remaining six dogs were killed for tensile testing. Micro-angiograms showed that the allogeneic tendon was revascularised with infiltration of the mesenchymal cells from the surrounding tissues and both ends of the graft. Histologically, the alignment of the fibroblasts and collagen bundles became more regular over time, without any immunological rejection. A biomechanical study performed at 52 weeks found no significant difference in stiffness or ultimate load between normal and reconstructed ligaments. Fresh-frozen allogeneic tendons are therefore considered useful for extra-articular ligament reconstruction

We have developed a simple technique for demonstrating the sagittal profile of each rotated level of a scoliotic spine and used it to determine the patterns of lordosis and kyphosis in each of six clinical types of idiopathic scoliosis. The currently accepted classification of scoliosis is inaccurate and a modification is proposed. The three main types of scoliosis were shown to have sagittal profiles distinctly different from each other and from normal. Single structural curves had short lordotic sections at their apices, limited above and below by kyphosis. Double curves showed longer lordotic sections limited only by one area of kyphosis. Lordosis throughout the thoracic and lumbar spine was associated with triple curve patterns. The biomechanical effects of the abnormal sagittal profiles provide a simple explanation for the genesis and progression of the different types of scoliosis, and the recognition of the pattern of the sagittal abnormalities permits treatment to be designed on a sound anatomical basis for individual cases

The Blauth prosthesis is a hinged total knee replacement. We have evaluated 422 consecutive primary total knee arthroplasties using this design in 330 patients with a maximum follow-up of 20 years (mean 6). The mean age of the patients at the time of operation was 70 years (29 to 87). Using endpoints of infection, removal because of aseptic loosening, removal for any cause, and the worst case as definitions of failure, the cumulative rates of survival at 20 years were 93.6%, 96.0%, 94.4% and 86.8%, respectively. The cumulative rate of survival of the patients themselves was 14.4% (24% in patients with osteoarthritis and 9% in these with rheumatoid arthritis) after 20 years. Our survivorship analysis shows that hinged knee prostheses, when they are biomechanically well designed, can yield a satisfactory long-term outcome, similar to those of the best prostheses of the resurfacing type. Hinged knee prostheses continue to be of value in patients with severe deformity or instability of the knee

The long flexor tendons of the second, third and fourth toes of 94 chickens were cut and sutured. After operation the birds were divided into three groups. To reduce peritendinous adhesions, an aqueous solution of beta-aminopropionitrile (BAPN) was added to a solution of enriched native collagen (ECS) and applied to the cut tendons of one group; untreated controls and controls treated with collagen solution alone comprised the other groups. Chickens from each group were killed one, two, three, four and five weeks after operation. The results were evaluated both biomechanically and biochemically. It was found that the collagen solution alone had the same effect as the treatment with BAPN. It is suggested that the exogenous collagen present at the site of injury binds the collagenase inhibitor released by tendon cells, thus providing enough active collagenase to control the formation of fibrous adhesions. The inefficiency of BAPN in these experiments might have been due to either inadequate dosage or wrong timing, or both

We have reviewed the long-term results of 22 patients (23 fusions) with fractures of the os calcis, who had subtalar arthrodesis with correction of the deformity between 1975 and 1991. The mean follow-up was nine years (5 to 20). All patients were evaluated according to a modified foot score. A radiological assessment was used in which linear and angular variables were measured including the fibulocalcaneal abutment, the height of the heel and fat pad, the angle of the arch and the lateral talocalcaneal and the lateral talar declination angles. The technique used restores the normal relationship between the hindfoot and midfoot and corrects the height of the heel. This leads to better biomechanical balance of the neighbouring joints and gives a favourable clinical outcome. The modified foot score showed a good or excellent result in 51% of the feet. Residual complaints were mostly due to problems with the soft tissues. Subjectively, an excellent or good score was achieved in 78% of the cases. After statistical analysis, except for the height of the heel and the degenerative changes in the calcaneocuboid joint, no significant difference was found in the measured variables between the operated and the contralateral side

Objectives

Opening wedge high tibial osteotomy (HTO) is an established surgical procedure for the treatment of early-stage knee arthritis. Other than infection, the majority of complications are related to mechanical factors – in particular, stimulation of healing at the osteotomy site. This study used finite element (FE) analysis to investigate the effect of plate design and bridging span on interfragmentary movement (IFM) and the influence of fracture healing on plate stress and potential failure.

Aims

Early implant migration measured with radiostereometric analysis (RSA) has been proposed as a useful predictor of long-term fixation of tibial components in total knee arthroplasty. Evaluation of actual long-term fixation is of interest for cemented components, as well as for cementless fixation, which may offer long-term advantages once osseointegration has occurred. The objective of this study was to compare the long-term migration with one- and two-year migration to evaluate the predictive ability of short-term migration data and to compare migration and inducible displacement between cemented and cementless (porous metal monoblock) components at least ten years postoperatively.

In 42 elderly patients, 33 women and nine men with a mean age of 72 years, we treated displaced fractures of the proximal humerus (34 three-part, 8 four-part) using a blade plate and a standard deltopectoral approach. Functional treatment was started immediately after surgery. We reviewed 41 patients at one year and 38 at final follow-up at 3.4 years (2.4 to 4.5). At the final review, all the fractures had healed. The clinical results were graded as excellent in 13 patients, good in 17, fair in seven, and poor in one. The median Constant score was 73 ± 18. Avascular necrosis of the humeral head occurred in two patients (5%). We conclude that rigid fixation of displaced fractures of the proximal humerus with a blade plate in the elderly patient provides sufficient primary stability to allow early functional treatment. The incidence of avascular necrosis and nonunion was low. Restoration of the anatomy and biomechanics may contribute to a good functional outcome when compared with alternative methods of fixation or conservative treatment. Regardless of the age of the patients, we advocate primary open reduction and rigid internal fixation of three- and four-part fractures of the proximal humerus

Objectives

Unicompartmental knee arthroplasty (UKA) is one surgical option for treating symptomatic medial osteoarthritis. Clinical studies have shown the functional benefits of UKA; however, the optimal alignment of the tibial component is still debated. The purpose of this study was to evaluate the effects of tibial coronal and sagittal plane alignment in UKA on knee kinematics and cruciate ligament tension, using a musculoskeletal computer simulation.

The healing of a hamstring graft to bone is the weak link in the reconstruction of a cruciate ligament using this donor material. We therefore investigated the augmentation of healing at the tendon-bone interface using calcium-phosphate cement (CPC). We performed semitendinosus autograft reconstructions of the anterior cruciate ligament on both knees of 22 New Zealand white rabbits. The interface between the grafted tendon and the bone tunnel for one knee was filled with CPC. Six rabbits were killed at the end of the first and second post-operative weeks in order to evaluate the biomechanical changes. Two rabbits were then killed sequentially at the end of weeks 1, 3, 6, 12 and 24 after operation and tissue removed for serial histological observation. Histological examination showed that the use of CPC produced early, diffuse and massive bone ingrowth. By contrast, in the non-CPC group of rabbits only a thin layer of new bone was seen. Mechanical pull-out testing at one week showed that the mean maximal tensile strength was 6.505 ± 1.333 N for the CPC group and 2.048 ± 0.950 N for the non-CPC group. At two weeks the values were 11.491 ± 2.865 N and 5.452 ± 3.955 N, respectively. Our findings indicate that CPC is a potentially promising material in clinical practice as regards its ability to reinforce the fixation of the tendon attachment to bone and to augment the overall effectiveness of tendon healing to bone

We performed a biomechanical study on human cadaver spines to determine the effect of three different interbody cage designs, with and without posterior instrumentation, on the three-dimensional flexibility of the spine. Six lumbar functional spinal units for each cage type were subjected to multidirectional flexibility testing in four different configurations: intact, with interbody cages from a posterior approach, with additional posterior instrumentation, and with cross-bracing. The tests involved the application of flexion and extension, bilateral axial rotation and bilateral lateral bending pure moments. The relative movements between the vertebrae were recorded by an optoelectronic camera system. We found no significant difference in the stabilising potential of the three cage designs. The cages used alone significantly decreased the intervertebral movement in flexion and lateral bending, but no stabilisation was achieved in either extension or axial rotation. For all types of cage, the greatest stabilisation in flexion and extension and lateral bending was achieved by the addition of posterior transpedicular instrumentation. The addition of cross-bracing to the posterior instrumentation had a stabilising effect on axial rotation. The bone density of the adjacent vertebral bodies was a significant factor for stabilisation in flexion and extension and in lateral bending

A vascularised fibular strut graft was used for anterior spinal fusion in 16 patients with spinal kyphosis. The procedure was abandoned in three because of difficulty in establishing a vascular anastomosis and in one because the grafted fibula dislodged two days after operation. One patient died after five days. Of the 11 remaining patients, there were seven males and four females. Their ages at the time of operation averaged 30.9 years (12 to 71). The number of vertebrae fused averaged 6.7 (5 to 9) and the length of fibula grafted averaged 10.9 cm (6.5 to 18). Average follow-up was 54 months (27 to 84). Bone union occurred at both ends of the grafted fibula in all 11 patients, with an average time to union of 5.5 months (3 to 8). We did not see a fracture of the grafted fibula. Two patients had postoperative complications; the graft dislodged in one and laryngeal oedema occurred two days after operation in the other. A vascularised fibular strut graft provides a biomechanically stable and long-standing support in spinal fusion because the weak phase of creeping substitution does not take place in the graft

Comminuted and displaced fractures of the inferior pole of the patella are not easy to reduce and it is difficult to fix the fragments soundly enough to allow early movement of the knee. We have evaluated the clinical effectiveness of the separate vertical wiring technique in acute comminuted fractures of the inferior pole of the patella. A biomechanical study was also performed using ten pairs of embalmed cadaver knees. A four-part fracture was made on the inferior pole of the patella and fixed by two separate vertical wires on one side and two pull-out sutures after partial patellectomy on the other. The ultimate load to failure in the first group was significantly higher than in the second (250.1± 109.7 N v 69.7 ± 18.9 N, p< 0.002), as was the stiffness (279.9 ± 76.4 N/mm v 23.2 ± 11.4 N/mm, p< 0.001). The separate wire technique was used in 25 patients with comminuted fractures of the inferior pole of the patella who were followed up for a mean period of 22 months (10 to 50). All the fractures healed at a mean of seven weeks (6 to 10). No breakage of a wire or infection occurred. The mean grading at the final follow-up was 29.5 points (27 to 30) using the Böstman method. This technique preserved the length of the patella, fixed the comminuted fragments of the inferior pole and avoided long-term immobilisation of the knee

1. A series of 154 patients who underwent anterior cervical discectomy and fusion has been studied. A detailed analysis of the first eighty-four patients who have been observed for periods of from one to eight and a half years is described. In sixty-eight patients the fusion was done with a keystone type of graft, in seventeen by a dowel (Cloward) graft. 2. Despite a preponderance of multiple level fusions in the keystone series, clinically better results (80·8 per cent excellent or good) were found in this group than in the dowel group (64·8 per cent excellent or good). 3. A biomechanical study has indicated the keystone graft to be more stable than a dowel graft under flexion and extension strains as well as lateral bending strain. The graft is more stable the closer it is to the line of "zero velocity.". 4. The three cases of non-union all occurred in the dowel group. The high incidence of fusion with the keystone technique is considered to be related to the type of graft, its method of seating, its depth of penetration, its larger surface area and the fact that raw cancellous bone of the adjacent vertebral bodies is in contact with the graft above and below

Objectives

Elevated proximal tibial bone strain may cause unexplained pain, an important cause of unicompartmental knee arthroplasty (UKA) revision. This study investigates the effect of tibial component alignment in metal-backed (MB) and all-polyethylene (AP) fixed-bearing medial UKAs on bone strain, using an experimentally validated finite element model (FEM).

Aims

The aim of the British Association for Surgery of the Knee (BASK) Meniscal Consensus Project was to develop an evidence-based treatment guideline for patients with meniscal lesions of the knee.

The properties of impacted morsellised bone graft (MBG) in revision total knee arthroplasty (TKA) were studied in 12 horses. The left hind metatarsophalangeal joint was replaced by a human TKA. The horses were then randomly divided into graft and control groups. In the graft group, a unicondylar, lateral uncontained defect was created in the third metatarsal bone and reconstructed using autologous MBG before cementing the TKA. In the control group, a cemented TKA was implanted without the bone resection and grafting procedure. After four to eight months, the animals were killed and a biomechanical loading test was performed with a cyclic load equivalent to the horse’s body-weight to study mechanical stability. After removal of the prosthesis, the distal third metatarsal bone was studied radiologically, histologically and by quantitative and micro CT. Biomechanical testing showed that the differences in deformation between the graft and the control condyles were not significant for either elastic or time-dependent deformations. The differences in bone mineral density (BMD) between the graft and the control condyles were not significant. The BMD of the MBG was significantly lower than that in the other regions in the same limb. Micro CT showed a significant difference in the degree of anisotropy between the graft and host bone, even although the structure of the area of the MBG had trabecular orientation in the direction of the axial load. Histological analysis revealed that all the grafts were revascularised and completely incorporated into a new trabecular structure with few or no remnants of graft. Our study provides a basis for the clinical application of this technique with MBG in revision TKA

Aims

Studying the indications for revision total hip arthroplasty (THA) may enable surgeons to change their practice during the initial procedure, thereby reducing the need for revision surgery. The aim of this study was to identify and describe the potentially avoidable indications for revision THA within five years of the initial procedure.