Biomechanics of the meniscus-meniscal ligament construct of the knee.

The menisci of the knee act primarily to redistribute contact force across the tibio-femoral articulation. This meniscal function is achieved through a combination of the material, geometry and attachments of the menisci. The main ligaments that attach the menisci to the tibia (insertional ligaments, deep medial collateral ligament), the femur (meniscofemoral ligaments, deep medial collateral ligament) and each other (the anterior intermeniscal ligament) are the means by which the contact force between tibia and femur is distributed into hoop stresses in the menisci to reduce contact pressure at the joint. This means that the functional biomechanics of the menisci cannot be considered in isolation and should be considered as the functional biomechanics of the meniscus-meniscal ligament construct. This article presents the current knowledge on the anatomy and functional biomechanics of the meniscus and its associated ligaments. Much is known about the function of the meniscus-meniscal ligament construct; however, there still remain significant gaps in the literature in terms of the properties of the anterior intermeniscal ligament and its function, the properties of the insertional ligaments, and the most appropriate ways to reconstruct meniscal function surgically.

The consequences of meniscectomy.

The menisci of the knee have an important role in load-bearing and shock absorption within the joint. They may also function as secondary stabilisers, have a proprioceptive role, and aid the lubrication and nutrition of the articular cartilage. Complete or partial loss of a meniscus can have damaging effects on a knee, leading to serious long-term sequelae. This paper reviews the consequences of meniscectomy and summarises the body of evidence in the literature regarding those factors most relevant to long-term outcome.

Management of suspected scaphoid fractures in accident and emergency departments--time for new guidelines.

INTRODUCTION: The objectives of this work were to assess the clinical knowledge of clinicians in the accident and emergency (A&E) departments in England & Wales and evaluate the current trend for the acute management of radiologically normal, but clinically suspected, fractures of the scaphoid. SUBJECTS AND METHODS: We conducted a telephone survey on 146 A&E senior house officers (SHOs) in 50 different hospitals. This survey assessed the clinicians' experience, their clinical and radiological diagnostic methods, and their initial treatment of suspected scaphoid fractures. RESULTS: The majority (55.8%) of SHOs performed only one clinical test to diagnose suspected scaphoid fractures. Overall, 41% were unable to cite the number of the radiographic views taken and only 10% of departments have direct access to further radiological investigation. There is wide variation in the early treatment of this injury, with the scaphoid cast used most commonly (46%). The majority of SHOs (89%) were unable to describe the features of immobilisation. The mean follow-up period was 10 days, and 53% of cases were followed-up by the senior staff in A&E. Of SHOs, 54% were not aware of any local guidelines for the management of suspected scaphoid fractures in their departments, and 92% were not aware of the existence of the 1992 British Association for Accident and Emergency Medicine (BAEM) guidelines. CONCLUSIONS: The clinical knowledge and the management of suspected scaphoid fractures in A&E are unsatisfactory. We, therefore, suggest that the dissemination of up-to-date guidelines could help to educate clinicians to provide better care to the patients.

An anatomical study of meniscal allograft sizing.

Meniscus-to-femoral condyle congruity is essential for the development of circumferential hoop stresses and thus function of the meniscus. When meniscal allograft transplantation is performed using bony anchorage of the insertional ligaments, accurate graft-to-host size matching is therefore essential. The standard method currently employed for size matching of meniscal allografts is to rely on plain radiographs of the host's knee, from which expected meniscal dimensions are measured. This study aimed to examine the correlation between tibial plateau dimensions and meniscal dimensions. We studied 44 donor tibial plateaus with medial and lateral meniscal allografts attached intact. Meniscal and tibial plateau dimensions were measured. Linear regression analysis was used to calculate expected meniscal dimensions from each specimen's plateau dimensions. Using specific medial and lateral tibial plateau width and length measurements, meniscal dimensions could be predicted with a mean error of only 5.0+/-6.4%. When predicting meniscal dimensions from only total bony plateau width, the mean error observed was 6.2+/-8.0%. The difference between the two methods was not statistically significant. The results suggest that meniscal dimensions can be predicted accurately from tibial plateau measurements, with only small mean errors. However, potential size mismatches should be carefully borne in mind by surgeons using meniscal allografts.

A biomechanical study of four different meniscal repair systems, comparing pull-out strengths and gapping under cyclic loading.

Most studies comparing the biomechanical properties of different meniscal repair systems have simply investigated load to failure. Meniscal tissue is highly anisotropic, and far weaker under tension in the radial direction. Radially oriented loading to failure may not therefore be the most physiologically relevant in vitro test for repair of circumferential tears, and determining gapping across repair sites under cyclical loading at lower loads may be of greater importance. Using bovine menisci, vertical circumferential incisions were repaired using a simple vertical 2-0 PDS suture, Meniscal Arrow, Meniscal Fastener or T-Fix. Repairs were tested by simple loading to failure in a materials testing machine, and by cyclic loading between 5 and 10 N for 25 cycles. Initial gapping across the repairs was measured using a digital micrometer, and the increase in gapping under cyclic loading measured using a Differential Voltage Reluctance Transducer. The mean loads to failure for each of the repair groups were: sutures 72.7 N, Arrows 34.2 N, Fasteners 40.8 N and T-Fix 49.1 N. The load to failure was significantly greater with sutures than with Arrows or Fasteners. The mean gapping across the repairs for each of the repair groups after 25 loading cycles were: sutures 3.29 mm, Arrows 2.18 mm, Fasteners 3.99 mm and T-Fix 3.47 mm. The mean gapping was significantly less with Arrows than with Sutures, Fasteners or T-Fix. These results confirm that meniscal repair by suturing gives the highest load to failure, but show that Arrows give superior hold under lower loads, with the least gapping across repairs under cyclic loading of the four methods tested.

The role of rehydration in the prevention of fat embolism syndrome.

We encountered three cases of young sportsmen developing fat embolism syndrome (FES) after sustaining isolated tibial shaft fractures whilst playing football. All fractures were treated with intra-medullary nails and all three patients were kept nil-by-mouth pre-operatively without intravenous fluids. Correction of shock is often quoted as an important factor in the prevention of FES. However, animal studies have shown that dehydration, as opposed to hypovolaemia, may also be of great importance. We therefore examined the specific gravity of the urine of 20 patients with musculoskeletal injuries sustained during sport. The mean urinary specific gravity was significantly higher than that of a control group of 10 members of staff. We emphasise the importance of adequate pre-operative rehydration, especially if injuries were sustained during heavy exercise, as this may reduce the risk of developing FES.

Meniscofemoral ligaments revisited. Anatomical study, age correlation and clinical implications.

The meniscofemoral ligaments were studied in 84 fresh-frozen knees from 49 cadavers. Combined anterior and posterior approaches were used to identify the ligaments. In total, 78 specimens (93%) contained at least one meniscofemoral ligament. The anterior meniscofemoral ligament (aMFL) was present in 62 specimens (74%), and the posterior meniscofemoral ligament (pMFL) in 58 (69%). The 42 specimens (50%) in which both ligaments were present were from a significantly younger population than that with one MFL or none (p < 0.05). Several anatomical variations were identified, including oblique fibres of the posterior cruciate ligament (PCL), which were seen in 16 specimens (19%). These were termed the 'false pMFL'. The high incidence of MFLs and their anatomical variations should be borne in mind during arthroscopic and radiological examination of the PCL. It is important to recognise the oblique fibres of the PCL on MRI in order to avoid wrongly identifying them as either a pMFL or a tear of the lateral meniscus. The increased incidence of MFLs in younger donors suggests that they degenerate with age.

The internet--friend or foe? A questionnaire study of orthopaedic out-patients.

OBJECTIVE: To examine patients' use of the Internet to obtain medical information, their opinions on the quality of medical Web sites, and their attitudes towards Internet-based consultations. DESIGN: Questionnaire study. PARTICIPANTS AND SETTING: 398 patients, aged 10-95 years, visiting the orthopaedic outpatient clinics of a London district general hospital over a 2-week period. MAIN OUTCOME MEASURES: (i) The rate of Internet use by patients; (ii) the perception of the quality of medical web sites; (iii) future intentions and attitudes towards Internet-based consultations; and (iv) concurrence between information obtained from Web sites and advice given by the orthopaedic surgeon in the clinic. RESULTS: From 369 respondents (response rate 93%), 55.3% of patients had accessed the Internet. Of these, 52.0% had obtained medical information from this source. Access was linearly correlated with age (r2 = 0.975, P < 0.01) and was also related to social status. Of the 12.3% of patients who had researched their particular orthopaedic condition, 20% reported that the advice received from the surgeon in the clinic contradicted that obtained from the Internet. A total of 35.7% of patients would undergo an Internet-based consultation, whilst a further 25.5% would consider this, depending on the medical condition in question. CONCLUSIONS: Over half of the patients studied were willing to access the Internet for medical information, with younger patients more likely to undertake this activity. Moreover, a significant proportion of respondents were willing to undergo an Internet-based consultation. The increased use of medical Web sites by patients raises important issues regarding the need for quality control, and impacts significantly upon the surgeon-patient relationship.

Metastatic papillary thyroid carcinoma presenting as a typical branchial cyst.

Two cases of papillary thryoid carcinoma presenting as a cystic lateral neck mass are reported. This tumour characteristically presents in patients under 40-years-old and in the presence of an occult primary tumour may mimic a branchial cyst. In such cases simple aspiration of the cyst will produce a chocolate-brown serous fluid which excludes the diagnosis of a branchial cyst and is characteristic of papillary thyroid carcinoma. Cytological examination of the fluid has a high degree of sensitivity and specificity in the diagnosis of thyroid malignancy and should avoid delay in diagnosis and unnecessary surgical exploration prior to definitive treatment.