70 patients who underwent dynamic MRI scanning for chronic anterior knee pain were retrospectively evaluated. All patients had been symptomatic for over a year. 43 patients had been treated conservatively and 27 had undergone surgical procedures (arthroscopy -13, lateral release- 9, tibial tubercle transfer 5). The extent of subluxation, tilt and cartilage abnormalities on MRI scans, during resisted extension were assessed. Functional scoring (Oxford, Lysholm and Tegner scores) was done through questionnaires and correlated with the radiological findings.

54 (77%) patients were found to have some patellofemoral abnormality on the scans. Subluxation was the most common finding with mild subluxation in 30, moderate in 18 and severe in 17 knees. Mild tilt was seen in 26 knees and moderate to severe tilt in 14 knees. Tilt was found in association with subluxation except in 8 cases. Grade 1 and 2 cartilage wear were seen in 13 knees and Grade 3 and 4 in 21 knees.

The “Tibial Tubercle to Trochlear Groove distance” (TTD) was measured in all knees and correlated with subluxation. The average distance was 13.5mm, 13.6mm and 18.8mm for mild, moderate and severe subluxation respectively. All patients with a TTD _ 20mm had moderate or severe subluxation. The specificity of a TTD _ 20mm for severe maltracking was 100% but the sensitivity was only 42%.

The TTD appears to be the single most significant parameter determining patella tracking. We have proposed an algorithm for the surgical and non-surgical treatment of chronic anterior knee pain. We recommend lateral release for those with moderate and severe subluxation and a tibial tubercle transfer as well in those with a TTD _ 20mm. The functional scores did not zshow a significant correlation with the grading of subluxation.

Purpose of the study: To develop a new treatment algorithm for patients with chronic anterior knee pain based on kinematic patella tracking MR imaging.

Methods and Results: Patients with anterior knee pain of more than one year duration and not responding to non-operative treatment, underwent kinematic MRI study. The provocative test was performed with the conventional MRI scanner and the patient extending the knee against resistance, the resistance provided by inflated beach ball. A retrospective analysis was done of first seventy patients, who had undergone this scanning technique.

On the imaging films, four measurements were made. They were patella subluxation, tilt, cartilage thickness and the Tibial Tubercle Trochlear distance (TTD). Patellar subluxation was classified as mild, moderate and severe. We found that a Tibial Tubercle Trochlea distance of 18mm had a specifity of 100% and a sensitivity of 89% for severe maltracking.

Conclusion: Kinematic MR Imaging is a useful investigation before considering operative treatment for patients with chronic anterior knee pain. Based on our study, we conclude that those patients with moderate lateral maltracking with a TTD< 18 mm should be offered lateral release and those with severe maltracking and TTD> 18mm should have a tibial tubercle transfer, in addition to lateral release.

Purpose of the study: To develop a new treatment algorithm for patients with chronic anterior knee pain based on kinematic patella tracking MR imaging.

Methods and Results: Patients with anterior knee pain of more than one year duration and not responding to non-operative treatment, underwent kinematic MRI study. The provocative test was performed with the conventional MRI scanner and the patient extending the knee against resistance, the resistance provided by inflated beach ball. A retrospective analysis was done of first seventy patients, who had undergone this scanning technique.

On the imaging films, four measurements were made. They were patella subluxation, tilt, cartilage thickness and the Tibial Tubercle Trochlear distance (TTD). Patellar subluxation was classified as mild, moderate and severe. We found that a Tibial Tubercle Trochlea distance of 18mm had a specifity of 100% and a sensitivity of 89% for severe maltracking.

Conclusion: Kinematic MR Imaging is a useful investigation before considering operative treatment for patients with chronic anterior knee pain. Based on our study, we conclude that those patients with moderate lateral maltracking with a TTD< 18 mm should be offered lateral release and those with severe maltracking and TTD> 18mm should have a tibial tubercle transfer, in addition to lateral release.

Aim: MRI examination of tibial tunnel enlargement after hamstring ACL surgery.

Methods and Results: 101 primary hamstring ACL reconstructions were carried out employing a transtibial over-the-top route with fixation provided by the Soffix buttonhole polyester double loop device (1186 N mean UTL to failure with young human cadaveric STG tendons). 24 were reviewed and bony tunnel enlargement was evaluated. 18 prospective reconstructions at 4 months and 6 randomly selected cases at a mean of 14 months were subjected to MRI scanning performed perpendicular to the tibial tunnel axis and the cross sectional area (CSA) was calculated with a computer programme.

In 7 cases there was no enlargement, in 5 cases there was cylindrical enlargement, in 12 cases there was conical enlargement but no cavitation was noted. A maximum mean CSA of 33% ± 38.84 sd was noted at the upper tibial tunnel exit whilst the CSA increase at the distal tibial tunnel entrance was 13% ± 16.77 sd.

In addition the MRI scan showed no evidence of excessive granulation tissue ingrowth or synovial fluid between the graft and the tunnel wall. It would appear that micro-motion which is a major factor in tunnel enlargement is eliminated by the combination of a tight fitting graft, the strength and stiffness of the fixation device and highly accurate, low stress placement of the tibial tunnel. Post operative KT 2000 arthrometric testing of the mean side to side difference (SSD) was 1.71 mm ± 1.82 sd confirming that the graft remained stiff in vivo.

Conclusion: We concluded that our technique avoids excessive tunnel enlargement and leads to greater post-operative graft stiffness than that reported in other series, where hamstring reconstruction has been employed.