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PubMed1982

Deformity of the proximal tibia in dogs.

A condition has been recognised in five young dogs in which the proximal tibia exhibited cranial bowing. This altered conformation, sometimes accompanied by bow legs (genu varum), occurs bilaterally, but to differing degrees. The deformity apparently altered the biomechanics of the stifle joint so that degenerative joint disease and rupture of the cranial cruciate ligament followed in four of the five dogs. The aetiology is unknown, but the most likely cause appears to be retardation of growth in the caudal aspect of the proximal tibial physis. Treatment involving surgical techniques to correct the joint instability was only moderately successful.

Animals↗
PubMed1987

Osteochondritis dissecans: analysis of mechanical stability with radiography, scintigraphy, and MR imaging.

Twenty-one joints with stable (n = 9) or loose (n = 12) osteochondritis dissecans (OCD) lesions were examined in 15 subjects with plain radiography, three-phase bone scintigraphy, and magnetic resonance (MR) imaging. The lesion size and the thickness of the sclerotic margin as measured on plain radiographs were good parameters for predicting loosening. However, bone scintigraphy was more sensitive and specific in determining the mechanical stability of OCD lesions. MR imaging permitted direct visualization of loosening and fragment displacement; the latter permits differentiation of in situ loosening from a grossly unstable lesion. The noninvasive nature of bone scintigraphy and MR imaging makes them potentially preferable diagnostic modalities to arthrography for evaluating the mechanical status of OCD lesions.

Adolescent↗
PubMed1998

Anterolateral impingement of the ankle: effectiveness of MR imaging.

PURPOSE: To determine the effectiveness of magnetic resonance (MR) imaging in the diagnosis of anterolateral impingement of the ankle. MATERIALS AND METHODS: MR images were reviewed in 12 patients (12 ankles) with arthroscopically proved anterolateral impingement and in 19 control subjects (20 ankles) with diagnoses other than impingement. MR images were scored by means of consensus of two musculoskeletal radiologists and independently by a third radiologist. Patients underwent imaging at 1.5 T, with use of standard imaging sequences and a dedicated extremity coil. RESULTS: For the consensus reading, the sensitivity, specificity, and accuracy of MR imaging for the diagnosis of impingement were 42%, 85%, and 69%, respectively. The frequency of lateral gutter fullness and anterior talofibular ligament thickening on MR images was higher in the 12 ankles with impingement (seven [58%] and seven [58%] ankles, respectively) than in the 20 control ankles (seven [35%] and five [25%] ankles, respectively), but these trends did not reach statistical significance. Interobserver agreement for anterior talofibular ligament thickening was high, whereas that for lateral gutter fullness was fair. CONCLUSION: Conventional MR imaging of the ankle is insensitive for anterolateral impingement. Anterior talofibular ligament thickening and soft-tissue fullness in the lateral gutter may be suggestive of the diagnosis, but the reliability of the latter finding is questionable.

Adult↗
PubMedDate not supplied

Spontaneous synovitis in Wistar rats.

Spontaneous synovitis has been detected in the stifle joints of control Wistar rats in 4-wk and 2-yr toxicity studies, and a specific site was found to be predisposed to synovitis. The incidence of synovitis was 27.5% for males in the 4-wk study and 40.0% for males and 16.0% for females in the 2-yr study. The severity was not increased with aging. The degenerative changes, including chondroid metaplasia of the cruciate ligaments of the stifle and/or the surrounding connective tissue at the border of the cruciate ligaments of the stifle, were present even in younger animals, and moreover there was a good correlation between synovitis and chondroid metaplasia of the cruciate ligaments of the stifle and the surrounding connective tissue at the border of the cruciate ligaments of the stifle. Vascular changes, including the development of fibrin-containing thrombi, were observed in the surrounding connective tissue at the border of the cruciate ligaments of the stifle. It is speculated that the pathogenesis of the observed synovitis reflects joint instability that induces mechanical damage of the synovium.

Age Factors↗
PubMedDate not supplied

Evaluation of unstable shoulders by computed tomography. A preliminary study.

Three patients who had various types of glenohumeral joint instability, and in whom computed tomography (CT) was utilized as an additional diagnostic modality, are presented. In two of the three patients, routine radiography supplemented with special views documented the presence of a Hill-Sachs lesion; in the third, an equivocal abnormality was apparent. In all three individuals, CT verified the presence of a Hill-Sachs lesion; in one patient, there was also a Bankart deformity. CT represents a new and important modality that may be applied to the diagnostic evaluation of patients with unstable shoulders.

Adult↗
PubMedDate not supplied

Articular mobility in ballet dancers. A follow-up study after four years.

A follow-up study of ballet dancers was conducted to determine the influence of 4 years additional training on articular mobility using Beighton's method. The score increased in 25 (45.5%) of the 55 dancers reexamined. Acquired forward flexion accounted for this increase in 21 (84%) of the 25 dancers. These 21 dancers had had significantly less training than had the 30 dancers who could forward flex when examined initially (P less than 0.0001), showing that forward flexion is acquired through training. There were significantly more hypermobile individuals among dancers who had continued dancing than among those who had stopped (P less than 0.03). However, only 2 (16.7%) of 12 dancers who had progressed in their careers were hypermobile. We conclude that 1) most ballet dancers are able to forward flex, 2) forward flexion is usually acquired and develops after 4 or more years of training, 3) the mobility score may assist in predicting who will continue dancing, but that 4) there is no association between hypermobility and dancing excellence.

Adolescent↗
PubMedDate not supplied

Articular hypermobility and chondral injury in patients with acute patellar dislocation.

Thirty adolescents with acute, primary patellar dislocation were assessed for a relationship between articular hypermobility and chondral injury. The 15 patients without articular hypermobility had a 2.5 times increased frequency of articular lesions when compared with 15 patients with hypermobility. Assessment of articular hypermobility should be part of the examination in patients with patellar dislocation.

Acute Disease↗
PubMed1986

Effect of surface replacement arthroplasty on stability of the ankle.

Loosening after total ankle arthroplasty may result from absorption of tensile and shear forces by relatively small bone-cement interfaces. A surface replacement arthroplasty similar in principle to the Oxford knee arthroplasty offers theoretical advantages over other designs. The ability of such a prosthesis to provide a stable articulation was tested by examination of ankle laxity before and after replacement of the tibiotalar articular surfaces. The motion response characteristics of four specimens were measured for internal-external rotation moment (+/- 3 nm), inversion-eversion moment (+/- 3 nm), and anteroposterior displacement (+/- 50 N). The prosthesis restored normal internal-external and inversion-eversion rotatory stability, but the mean anteroposterior laxity was increased from 5.5 to 9.7 mm (P less than 0.05). Anteroposterior stability could not be restored by increasing the thickness of the bearing interposed between the prosthetic surfaces. The findings can be explained by consideration of the anatomy of the ligaments in relation to the contour of the normal and prosthetic articular surfaces. The normal tibial articular surface, which is concave in the sagittal plane, provides restraint against anteroposterior motion which is lost when the surface is replaced by the flat prosthetic surface. The findings question the suitability of this type of prosthesis for the ankle.

Ankle Joint↗
PubMed1988

High resolution computed tomography in the chronically painful ankle sprain.

A series of 31 consecutive patients with chronic residual ankle pain following ankle sprain were analyzed using high resolution CT scanning. In 13 patients avulsed intra- or juxta-articular fragments of traumatic origin were detected; 12 of these patients had surgical revision. The usefulness of CT scanning in chronic post-traumatic residual ankle pain in the presence of negative standard x-rays is stressed.

Adolescent↗
PubMed2000

Severe injuries in football players. Influencing factors.

The aims of this prospective study were to analyze factors related to the occurrence of severe football injuries in players of different ages (14 to 42 years) and different skill levels (local teams to first league teams). In the Czech Republic, 398 players were followed up for 1 year, during which time they sustained 686 injuries. Of these, 113 (16.5%) were severe injuries. Ninety-seven severe injuries (86%) were able to be documented in detail. Trauma was the cause of 81.5% of the injuries and overuse was the cause of 18.5%. Joint sprains predominated (30%), followed by fractures (16%), muscle strains (15%), ligament ruptures (12%), meniscal tears and contusions (8%), and other injuries. Injuries to the knee were most prevalent (29%), followed by injuries to the ankle (19%) and spine (9%). More injuries occurred during games (59%) than in practice. Twenty-four percent of the injured players had suffered a previous injury of the same body part. Forty-six percent of injuries were caused by contact and 54% involved no body contact. Thirty-one percent of severe injuries were caused by foul play. From these results and the analysis of injuries in specific body parts, the following factors were determined to influence the occurrence of severe injuries: 1) personal factors (intrinsic): age of player, previous injuries, joint instability, abnormality of the spine, poor physical condition, poor football skills, or inadequate treatment and rehabilitation of injuries; 2) environmental factors (extrinsic): subjective exercise overload during practices and games, amount and quality of training, playing field conditions, equipment (wearing of shin guards and taping) and violations of existing rules (foul play).

Adolescent↗
PubMed2006

Case report: intra-tendinous ganglion of the anterior cruciate ligament in a young footballer.

A 20-year-old male medical student and keen rugby player presented with a 12-month history of progressively worsening right knee pain and stiffness with no history of trauma. Clinical examination revealed effusion and posterior knee pain exacerbated by end range movement and an extension lag of 15 degrees. Physiotherapy to improve the range of motion proved unsuccessful. Magnetic resonance imaging showed that the ACL was grossly thickened and displaced by material reported as mucoid in nature. There were also areas of focally high signal in relation to its tibial attachment and intra osseous small cysts. Arthroscopic examination revealed a ganglion related to the tibial attachment of the ACL and gross thickening and discoloration of the ACL. Biopsies were taken showing foci of mucoid degeneration in the ACL. A large intra-ACL mass of brownish coloured tissue was excised arthroscopically. Already at 2 weeks follow up the patient had greatly improved range of movement and was pain free. However, upon returning to rugby, joint instability was noticed and a tear of the ACL was confirmed. This rare clinical condition can be diagnosed with MRI and arthroscopic debridement effectively relieves symptoms. This case report illustrates that augmentation or reconstruction may end up being the definitive treatment for athletes. It may also offer some support to the argument that mucoid degeneration and ganglion cyst formation share a similar pathogenesis to intra-osseous cyst formation.

Journal Article↗
PubMed2004

Prediction of scratch resistance of cobalt chromium alloy bearing surface, articulating against ultra-high molecular weight polyethylene, due to third-body wear particles.

The entrapment of abrasive particles within the articulation between a cobalt chromium alloy (CoCrMo) femoral component and an ultra-high molecular weight polyethylene (UHMWPE) cup of artificial hip joints or tibial inserts of artificial knee joints usually scratches the metallic bearing surface and consequently increases the surface roughness. This has been recognized as one of the main causes of excessive polyethylene wear, leading to osteolysis and loosening of the prosthetic components. The purpose of this study was to use the finite element method to investigate the resistance of the cobalt chromium alloy bearing surface to plastic deformation, as a first approximation to causing scratches, due to various entrapped debris such as bone, CoCrMo and ZrO2 (contained in radiopaque polymethyl methacrylate cement). A simple axisymmetric micro contact mechanics model was developed, where a spherical third-body wear particle was indented between the two bearing surfaces, modelled as two solid cylinders of a given diameter, under the contact pressure determined from macro-models representing either hip or knee implants. The deformation of both the wear particle and the bearing surfaces was modelled and was treated as elastic-plastic. The indented peak-to-valley height on the CoCrMo bearing surface from the finite element model was found to be in good agreement with that reported in a previous study when the third-body wear particle was assumed to be rigid. Under the physiological contact pressure experienced in both hip and knee implants, ZrO2 wear particles were found to be fully embedded within the UHMWPE bearing surface, and the maximum von Mises stresses within the CoCrMo bearing surface reached the corresponding yield strength. Consequently, the CoCrMo bearing surface was deformed plastically and the corresponding peak-to-valley height (surface roughness) was found to increase with both the hardness and the size of the wear particle. Even in the case of CoCrMo wear particles, with similar mechanical properties to those of the CoCrMo bearing surface, a significant plastic deformation of the bearing surface was also noted; this highlighted the importance of considering the deformation of the wear particles. These findings support the hypotheses made by clinical studies on the contribution of entrapped debris to increased surface roughness of CoCrMo femoral bearing surfaces.

Compressive Strength↗
PubMed1984

The development of an unconstrained elbow arthroplasty. A clinical review.

This paper describes the development, operative technique and results of an unconstrained total elbow arthroplasty. Forty-seven elbow replacements were carried out in 44 patients between 1974 and 1982. There was a high rate of loosening in the early condylar replacements. The results in patients with post-traumatic arthritis were poor. The later design employs an ulnar stem, with a humeral stem if the distal humeral bone stock is poor. When used in carefully selected patients with rheumatoid arthritis, pain is reduced significantly, stability and movement are preserved and function is improved.

Adult↗
PubMed1992

Kinematics of semi-constrained total elbow arthroplasty.

We used 11 cadaver elbows and a three-dimensional electromagnetic tracking device to record elbow movements before and after implantation of a 'loose-hinged' elbow prosthesis (modified Coonrad). During simulated active motion there was a maximum of 2.7 degrees (+/- 1.5 degrees) varus/valgus laxity in the cadaver joints. This increased slightly after total elbow arthroplasty to 3.8 degrees (+/- 1.4 degrees). These values are lower than those recorded for the cadaver joints and for the prostheses at the limits of their varus/valgus displacements, indicating that both behave as 'semi-constrained' joints under physiological conditions. They suggest that the muscles absorb some of the forces and moments that in a constrained prosthesis would be transferred to the prosthesis-bone interface.

Biomechanical Phenomena↗
PubMed1998

Non-constrained elbow arthroplasty for mutilans deformity in rheumatoid arthritis: a report of six cases.

Six highly unstable elbows with severe bone loss due to rheumatoid arthritis were replaced by a non-constrained, unlinked prosthesis. Bone defects were filled with autogenous bone grafts. The mean follow-up was 4.5 years (2 to 8). The clinical results were excellent in four elbows and good in two, with good varus-valgus stability in all. Radiological follow-up showed no appreciable signs of loosening, and the bone grafts had retained most of their original size, with minimal resorption. There were no major complications such as dislocation, skin necrosis, infection or ulnar neuropathy. The study has shown that the so-called mutilans elbow can be successfully replaced using a properly selected type of non-constrained, unlinked prosthesis with bone grafting of the major defects.

Alloys↗
PubMed2002

Bone ingrowth in the presence of particulate polyethylene. Synergy between interface motion and particulate polyethylene in periprosthetic tissue response.

We have investigated whether the presence of polyethylene (PE) alone is sufficient to cause an aggressive periprosthetic tissue response, or whether certain mechanical interface conditions can allow bone to grow while in the presence of PE. An experimental implant was loaded in the presence and absence of particulate PE under stable and unstable conditions. Bone with a thin, discontinuous fibrous membrane formed in both groups of stable implants, either in the presence or absence of PE. By contrast, a continuous fibrous membrane consistently formed in both groups of unstable implants. The membrane consisted of loose fibrous connective tissue when PE was absent, and dense connective tissue with macrophages and a synovial lining when PE was present. In this model, if the interface was stable, the presence of PE was not sufficient to prevent the formation of bone or to produce a phagocytic tissue response. Only when the interface was unstable did a fibrous membrane form, and only then in the presence of PE.

Animals↗
PubMed2005

The effect of accuracy of implantation on range of movement of the Scandinavian Total Ankle Replacement.

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.

Aged↗
PubMed2005

Spectrum of injuries from glacial sports.

OBJECTIVE: Glacial sports continue to be a popular form of wilderness activity, but no published studies have commented on this type of sport or focused on the injury patterns of glacial accidents. The objectives of this study were to investigate the types and frequency of injuries associated with a glacial-crevasse or ice-field fall. METHODS: The trauma registry data and radiology record system of a pediatric and adult level 1 trauma center were evaluated from January 1997 through August 2003. All admissions with injuries caused by a glacial-crevasse or ice-field fall were reviewed. RESULTS: During the 5 1/2-year period we identified 12 patients, of whom 9 (75%) were male. The average age was 30.2 years with an age range of 9 to 57 years. Six patients fell into glacial crevasses, and the other 6 slid down an ice field of a glacier. Leading diagnoses were head injury (44.6%), thorax injury (20.1%), and lower extremity injury (18.4%). Serious injuries were observed in 66.6% of the patients with a Glasgow Coma Scale of 3 to 8. CONCLUSIONS: A wide spectrum of injuries is associated with glacial accidents. They range from common extremity injuries with fracture or joint instability and peripheral frostbite to potentially life-threatening nonorthopedic trauma, which requires intensive clinical and radiological work-up. Injury prevention strategies should focus on wearing helmets to reduce head injuries and adequate clothing to forestall or prevent hypothermia, for these are the most severe and life-threatening injuries.

Adolescent↗