This paper reports a series of comparative tests in-vitro that examined how lateral meniscectomy and meniscal allografting affected tibio-femoral joint contact pressures. 8 Cadaver knees (age range 81 – 98 years) were loaded in axial compression in an Instron materials testing machine up to 700N for 10 seconds and pressure maps obtained from the lateral compartment using Fuji Prescale film inserted below the meniscus. This was repeated after meniscectomy, then after meniscal allografting with fixation by a bone plug for the insertional ligaments, plus peripheral sutures. Finally, the pressure when the allograft was secured by peripheral sutures alone was measured.

Meniscectomy caused a significant increase in peak contact pressures (p=0.0002). Both of the reconstructive methods reduced the peak contact pressures significantly below that of the meniscectomised knee (p=0.0029 with bone block; p=0.0199 with sutures alone). A significant difference was not found between the peak contact pressures after the reconstructions and that of the intact knee (p=0.1721 with bone block; p=0.0910 with sutures alone). The peak pressures increased slightly when the allografts were converted from bone block to suture-only fixation (p=0.0349).

The principal finding was that both of the meniscal allograft insertion techniques reduced the peak contact pressure significantly below that of the meniscectomised knee, so that it did not then differ significantly from the peak contact pressure in the intact knee. When the two fixation methods were compared, the loss of the bone plug attachment caused a small increase in peak pressure.

This study suggests that meniscal allografting should have a chondroprotective effect and that there is a small advantage from adding bony fixation to suture fixation.

Aims: To evaluate different surgical techniques of lateral meniscal allograft transplantation in cadaver knees, and to assess how these techniques affect tibial contact pressures.

Methods: The femoral and tibial shafts of five human cadaver knees were cemented into steel pots. Fresh-frozen irradiated human meniscal allografts were supplied by the East Anglia Tissue Services Department of the National Blood Service.

The knees were mounted into an Instron materials testing machine. Paddles of pressure-sensitive Fuji Prescale Film were inserted into the lateral compartment of the knee, underneath the lateral meniscus. Each knee was then loaded to 700N for 10 seconds. The Fuji Film paddles were digitally scanned and then analysed using Scion Image Analysis software to determine the intra-articular contact pressures.

Contact pressures were then determined after (i) total lateral meniscectomy, (ii) lateral meniscal allograft transplantation using a bone plug-keyhole technique to secure the horn attachments, and (iii) after insertion of the graft by suturing only.

Results: Total lateral meniscectomy led to a mean increase in maximum contact pressures of 103% (s.d. 63). Mean maximum contact pressures after lateral meniscal transplantation with a bone cylinder were 59% (s.d. 60) greater than the intact state, and after suturing only of the graft, were 85% (s.d. 74) greater than the intact knees.

Conclusions: Overall, lateral meniscal transplantation did partially restore contact pressures within the knees, and the use of a graft attached to a bone cylinder appeared to be more effective than just simple suturing of the graft. However, the results varied greatly between the different knees. In two knees, the results of meniscal transplantation were excellent. However, results were poor in knees with inaccurate graft-to-host size matching or where there was significant articular degeneration.

Introduction: Accurate size-matching of meniscal allografts is essential to maintain tibiofemoral congruity, and therefore function, especially when the surgical technique of using a bony bridge is employed.

Methods of accurately assessing the required dimensions of an ideal meniscal allograft for each patient are limited. One popular method used is to choose the appropriate graft according to the bony tibial plateau dimensions of the patient, as determined from plain radiographs.

Aims: To correlate meniscal dimensions with the bony dimensions of donor tibial plateaus.

Methods: 22 left and right pairs of donor tibial plateaus with intact meniscal allografts were obtained, giving a total of 88 individual meniscal allografts. Using a digital micrometer, the following meniscal dimensions were measured: anteroposterior length, medial-lateral width, and the radial width at the mid-point of the meniscal body. Peripheral circumference was measured using flexible steel wire. Medial and lateral bony tibial plateau width and length, and total plateau width were also recorded.

Linear regression analysis was used to obtain a formula, relating each meniscal dimension to the various bony plateau measurements. The resulting equations were used to calculate an expected meniscal dimension from the measured plateau dimensions, and this was compared to the size of the actual dimension measured.

Results: The magnitude of the meniscal dimensions measured approximately fitted a normal distribution amongst all the specimens studied. The tibial plateau widths ranged from 69.2mm to 88.4mm (mean 78.5mm, s.d. 5.4mm), a 28% difference. The mean difference between meniscal measurements between the left and right knee of each pair was 7.3%. However, the greatest individual difference observed was 41.8%.

The mean percentage error between meniscal dimensions calculated from specific compartmental tibial plateau dimensions, and the actual measured meniscal dimensions was 5.3% (s.d. 4.1%). When using just total bony tibial plateau width to calculate meniscal dimensions, the percentage error was 6.2% (s.d. 4.9%). This difference was not statistically significant. The maximum error between calculated and actual meniscal dimensions was 32%.

Conclusions: This anatomical study shows that the use of plateau dimensions as a determinant for the sizing of meniscal allografts can be used to predict meniscal dimensions. However, mean errors are in the region of 5% – 6%, and can be as high as 32%. The potential mechanical effects of such graft to host size mismatching must be carefully borne in mind.

The menisci function within the knee as load distributors, shock absorbers and secondary stabilisers. The medial meniscus has been shown to carry as much as 50% of the load across the medial compartment, and the lateral meniscus 70% of its compartmental load. After total meniscectomy, joint contact areas decrease by approximately 75%, and peak local contact stresses increase by as much as 235%. Meniscectomy may lead to a 14 times increase in the risk of arthritis at 20 years.

Axial load across the knee is converted into hoop stresses along the circumferential collagen fibres within the meniscus. Strong and stiff attachment of both meniscal horns, via the insertional ligaments, to the tibia is essential. Disruption of the circumferential fibre arrangement will defunction the meniscus. Preservation of meniscal tissue, where possible and appropriate, is now accepted practice.

Most techniques for meniscal repair have been validated in vitro by testing radial pull-out strengths. However, meniscal tissue is highly anisotropic, with little strength in the radial direction, perpendicular to the circumferential collagen fibres. Physiological forces in the radial direction, across the menisci, are probably only very small. Therefore, mechanical evaluation of radial pull-out strengths is probably of little clinical significance.

The role of different repair techniques, and the significance of gapping across repair sites under cyclical loading will be discussed.

Studies comparing the biomechanical properties of different meniscal repair systems are limited, and most have simply investigated load to failure. Meniscal tissue is highly anisotropic, and far weaker under tension in the radial direction. Loading to failure using high radially orientated loads may, therefore, not be the most physiologically relevant in-vitro test for repair of circumferential tears, and determining increases in gapping across repair sites under cyclical loading at lower loads may be of greater importance. This study aimed to determine the load to failure for 4 different meniscal repair techniques, and to assess gapping across repairs under cyclical loading.

Bovine menisci were divided vertically, 5mm from the peripheral edge to simulate a circumferential tear, and then repaired using 1 of 4 techniques: vertical loop sutures using 2-0 PDS, bioabsorbable Meniscal Arrows (Atlantech), T-Fix Suture Bars (Acufex) or Meniscal Fasteners (Mitek). 9 specimens were tested in each group using an Instron 5565 materials testing machine with Merlin control software to determine load to failure. A further 9 specimens in each group were tested by cyclical loading between 5N and 10N at 20mm/min for 25 cycles. Gapping across the repairs under cyclical loading was measured using a digital micrometer and a Differential Voltage Reluctance Transducer.

The peak load to failure values for each repair method did not appear to fit a Gaussian distribution, but were skewed to the left due to some samples failing at lower loads than the main cluster. Results were analysed using the Kruskal-Wallis test, with Dunn’s multiple comparison post test. The results for gapping across the repairs from the cyclical testing all appeared to fit the Gaussian distribution, and these were analysed by Analysis of Variance, with Tukey’s multiple comparison post test. All analysis was performed using Prism (Graph-pad) Software.

The mean loads to failure for each of the repair groups were: Sutures 72.7 N, T-Fix 49.1 N, Fasteners 40.8 N, and Arrows 34.2 N. The load to failure was significantly greater with the Suture group compared to the Arrows (p< 0.01) or the Fasteners (p< 0.05). The mean gapping across the repairs for each of the repair groups after 25 loading cycles were: Sutures 3.29mm, Arrows 2.18mm,Fasteners 3.99mm,andT-Fix 3.47mm.The mean gapping was significantly less for the Arrows compared to the Sutures (p< 0.05), the Fasteners (p< 0.01), or the T-Fix (p< 0.05).

The 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 cyclical loading by this testing protocol.

The objective of this study was 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.

The study made use of a questionnaire given to 398 patients, aged 10 to 95 years (mean 55 years), visiting the orthopaedic outpatient clinics of a London district general hospital over a 2 week period. The major outcome measures were; 1) the rate of Internet use by patients, 2) the perception of the quality of medical websites, 3) future intentions and attitudes towards internet-based consultations, and 4) concurrence between information obtained from Web sites and advice given by the orthopaedic surgeon in the clinic. Results were considered significant at p< 0.05. The Chi² test was used to compare proportions. Spearman’s correlation coefficients were used to quantify correlation.

From 369 respondents (response rate 91%), 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 clinical contradicted that obtained from the Internet. A total of 37.5% of patients would undergo an Internet-based consultation, whilst a further 25.5% would consider this, depending on the medical condition in question.

This is the first detailed UK study examining patient attitude towards Web-based medical learning. Over half of the patients were willing to access the Internet for medical information, with younger patients more likely to undertake this activity. As the commercial advantages of a captive patient population become apparent, there is the potential for inaccurate or misleading information, that has not undergone peer review, to be disseminated over the Internet The increased use of medical Websites by patients raised important issues regarding the need for quality control, which orthopaedic surgeons and their institutions both need to address. This also impacts significantly upon the changing nature of the surgeon-patient relationship.