Comparative Study on Insall-Salvati Index by Radiological and Clinical Methods in a Tertiary Care Centre of North Bengal, India

Knee Diameter and Cross-Section Area Measurements in MRI as New Promising Methods of Chondromalacia Diagnosis-Pilot Study

Background and Objectives: Chondromalacia often affects the knee joint. Risk factors for the development of cartilage degenerative changes include overweight, female sex and age. The use of radiological parameters to assess the knee joint is rarely reported in the literature. Materials and Methods: The study involved 324 patients, including 159 (49%) women and 165 (51%) men, with an age range between 8−87 years (mean: 45.1 ± 20.9). The studied group had a body mass index (BMI) in the range of 14.3−47.3 (mean: 27.7 ± 5.02). A 1.5 Tesla and 3.0 Tesla (T) MRI scanner was used to assess the cartilage of the knee joint using the Outerbridge scale. The radiological parameters analyzed were the Insall−Salvati index, knee surface area, knee AP (antero-posterior) maximal diameter and knee SD (sinistro-dexter) maximal diameter. Results: Parameters such as the knee surface area, knee AP maximal diameter and knee SD maximal diameter showed a significant correlation with Outerbridge Scale (p < 0.014). The age of the patients showed a significant correlation with each knee parameter (p < 0.004). Results of knee AP and SD maximal diameter measurements strongly depended on BMI level. Conclusions: A significant relationship was found between the knee surface area, knee AP maximal diameter and knee SD maximal diameter and the advancement of chondromalacic changes in the knee joint, age and BMI.

The Effect of Patellar Height by Using Insall Salvati Index on Pain, Function, Muscle Strength and Postural Stability in Patients with Primary Knee Osteoarthritis

PURPOSE

The Insall-Salvati Index (ISI) is the ratio of the patellar tendon length to the length of the patella. This ratio is the most commonly used method for evaluating patellar placement and patellofemoral imbalance. The position of the patella is important for the knee joint function and also for biomechanics. The abnormal position of the patella may lead to patellofemoral malalignment and instability. Herein, we aimed to analyze the relationship between the ISI and pain, physical function, muscle strength, fall risk, and postural stability in patients with primary knee osteoarthritis (OA).

METHODS

Sixty-two symptomatic knees of 45 patients (aged between 40 -75 years) who were suffering from the primary knee OA according to the American College of Rheumatology criteria were included retrospectively in the study. Patients with stages II and III osteoarthritis according to the Kellgren-Lawrence (K/L) radiological grading system were included. The ISI was measured on the lateral knee radiograph in a 30° flexed posture. Visual Analogue scale (VAS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC) and Lequesne indexes were recorded for evaluating pain and function. Tetrax Interactive Balance System was used to assess fall risk and postural stability. Isokinetic muscle strength measurements of quadriceps and hamstrings were recorded at the constant angular velocities of 60 and 180°/sec.

RESULTS

The mean age of the study population was 58.52 ±8.01 years. The frequency of the patellar situation types was as follows; patella alta; 15 (24.2%), patella baja; n=2(3.2%), and normal patellar height; n=45(72.6%). The mean ISI was 1.19 ±0.17 on the right side and 1.18±0.16 on the left side. There was no significant correlation between the ISI and VAS, WOMAC and Lequesne indexes, postural stability scores, and isokinetic measurements (r<0.3, p>0.05).

CONCLUSION

In primary knee OA, the ISI may not have an effect on pain, physical function, fall risk, postural stability, and isokinetic muscle strength.

CLINICAL TRIAL REGISTRATION NUMBER

KA18/170.