MEFV mutations in systemic onset juvenile idiopathic arthritis

OBJECTIVES

Autoinflammatory diseases constitute a large spectrum of monogenic diseases like FMF or cryopyrin-associated periodic syndromes (CAPS) and complex genetic trait diseases such as systemic onset juvenile idiopathic arthritis (SoJIA). An increased rate of MEFV mutations has been shown among patients with PAN and HSP, in populations where FMF is frequent. The aim of the study is to search for MEFV mutations in our patients with SoJIA and see whether these mutations had an effect on disease course or complications.

METHODS

Thirty-five children with the diagnosis of SoJIA were screened for 12 MEFV mutations. The control data were obtained from a previous study of our centre determining the carrier frequency in Turkish population.

RESULTS

Two patients were homozygous and three patients were heterozygous for the M694V mutation. One patient was a compound heterozygote for the M680I/V726A mutations. Heterozygous V726A mutation was found in one patient. The overall mutation frequency of patients was 14.28%. This figure had been compared with the previously published rate of disease-causing mutations in this country, which is 5%. Disease-causing mutations were found to be significantly more frequent in the SoJIA patients than the population (P < 0.01). Among these, M694V was the leading mutation with a frequency of 10% in SoJIA. Six patients carrying MEFV mutations were among the most resistant cases requiring biological therapy.

CONCLUSION

SoJIA patients had a significantly higher frequency of MEFV mutations but clinical studies with large number of patients are needed to confirm the association of MEFV mutations with SoJIA and its course.

A cross-sectional analysis of sagittal knee laxity and isokinetic muscle strength in soccer players

In this cross-sectional study, sagittal knee laxity and isokinetic strength of knee extensor and flexor muscle groups were measured and differences related to leg dominance were evaluated. A total of 44 healthy male soccer players (who had trained regularly at least for the last five years) and 44 sedentary people as their control counterparts were involved in this study. All participants were tested using a KT-1000 knee arthrometer for knee laxity. Isokinetic concentric knee peak torque and hamstring/quadriceps (H/Q) ratio were also measured at 60, 180, 300 degrees/s through a Cybex 2 - 340 dynamometer. Posterior laxity in the non-dominant side of soccer players was significantly higher than in the dominant side (p < 0.005) while there were no significant anterior and total anteroposterior (total AP) laxity differences in both groups. Soccer players had significantly lower anterior and total AP laxity values than controls (p < 0.0001) while there was no significant difference between posterior laxity values in both sides. Dominant extremity demonstrated significantly higher knee flexor peak torque and H/Q ratio at 180 degrees /s in soccer players (p < 0.05). Similarly in sedentary controls, H/Q ratio at 60 degrees /s of the dominant side was significantly higher than that in the non-dominant side (p < 0.05). Soccer players had significantly higher extensor and flexor peak torque values and H/Q ratios than sedentary subjects for both extremities. In both groups, there were no significant correlations between knee laxity and isokinetic knee extensor and flexor strength and H/Q ratios except weak negative correlation between posterior knee laxity and isokinetic extensor peak torque at 60, 180 and 300 degrees /s (p < 0.005, r = - 0.43, p < 0.05, r = - 0.39, p < 0.05, r = - 0.32 respectively) in the non-dominant side of soccer players and at 300 degrees /s (p < 0.05, r = - 0.32) in the non-dominant side of controls. Soccer players demonstrated significantly less sagittal knee laxity and higher isokinetic strength of the knee flexors and extensors compared to sedentary controls. Isokinetic strength difference was found to be higher for the flexor muscle group. Further prospective studies are needed to explain whether the increased H/Q ratio decreases the risk of ligamentous injury.

Effect of the vastus medialis obliquus on the patellofemoral joint

In this study, the effect of dynamic stabilizers on the patellofemoral (PF) joint was investigated in normal volunteers (group I) and in patients with patellar pain (group II) or instability (group III) by using computed tomography (CT) analysis and integrated electromyography (iEMG) of the quadriceps muscle. Nine subjects (16 knees) from group I, 10 patients (12 knees) from group II and 8 patients (12 knees) from group III were included in the study. CT scans of the PF joint with quadriceps contracted (QC) and uncontracted (QU) and iEMG of vastus medialis obliquus (VMO), vastus lateralis (VL) and rectus femoris (RF) were obtained with the aid of a specially designed jig at 0 degree, 15 degrees, 30 degrees and 45 degrees of knee flexion. The same muscle contraction pattern simulating closed kinetic chain exercise was used for both CT and iEMG. The difference between the congruence angles (CA) and tilt angles (PTA) in QC and QU positions and VMO:VL ratio from the iEMG were calculated separately for each flexion angle. CA was increased in all groups with quadriceps contraction at 0 degree and 15 degrees of flexion. PTA was decreased in group I and increased in groups II and III with quadriceps contraction at the same flexion angles. This difference was statistically significant in group III at 0 degree and 15 degrees of flexion. Quadriceps contraction did not affect the patellar position significantly even in the instability group at 45 degrees of flexion. In all flexion angles the balanced VMO:VL activity ratio was observed only in group I. In the other groups, VL activity was higher than VMO activity except at 45 degrees of flexion. These findings do not support the hypothesis of dominant centralizing effect of VMO on the patella in extension, but the effect of the VMO may be more clearly demonstrated by measuring PTA in both QC and QU positions.

Articular cartilage homeostasis after anterior cruciate ligament reconstruction

Several factors may be responsible for osteoarthritis after anterior cruciate ligament (ACL) reconstruction. The detrimental effect of the surgical technique may explain part of the progression of the pathologic process. In this study, the effect of ACL reconstruction on articular cartilage was investigated by measuring proteoglycan fragments (PF) in synovial fluid collected from patients who had undergone this operation. Synovial samples were obtained from 44 patients with chronic ACL deficiency aged 26 +/- 7 years preoperatively, and from some of them, samples were collected for monitoring at 1 month (n = 22), 3 months (n = 17), 6 months (n = 18) and 12s month (n = 18). Synovial fluid taken from 12 contralateral asymptomatic knees of 12 patients (not necessarily opposite knees of ACL-deficient cases) served as controls. Preoperative values were significantly larger than controls (P < 0.05). PF level reached its maximum value in the 1st month (P < 0.05) and then gradually decreased. It was significantly lower than preoperative values at 6 and 12 months but still greater than controls (P < 0.05). It seems that surgical trauma affects cartilage metabolism for the first 3 months postoperatively. Although reconstruction of the ACL contributes to articular cartilage homeostasis, a complete return to normal values cannot be achieved in 1st postoperative year at least in knees with chronic ACL deficiency. Long-term monitoring is needed to see whether these findings are early signs of osteoarthritis. Further studies may more clearly demonstrate the effect of the surgical procedure on knees with acute and subacute ACL deficiency.

Effect of tibial tubercle elevation on patellofemoral compressive force in patellofemoral arthrosis

In this study, the effect of tibial tubercle elevation on the patellofemoral compressive force (PFCF) was investigated in patients with patellofemoral arthrosis. Fifteen (11 women and 4 men) patients who had undergone tibial tubercle elevation were included in the study. The average follow-up was 4.5 years. The mean age of the patients was 59 years (range 34-71 years). They were able to maintain a normal pain-free daily life. Maximal isometric quadriceps force (Q) was calculated by equating the moment generated by this force to the moment of the force measured at the ankle by a modified hand dynamometer. PFCF was calculated from the quadriceps and patellar tendon forces. Statistical analyses were then applied to the measured and calculated quantities. The mean quadriceps force in the operated knee decreased by 20%. Likewise, the mean PFCF was found to be reduced by 30% in the operated knees as compared with the asymptomatic contralateral knees. The above differences in Q and PFCF between the operated knee and the asymptomatic knee were statistically significant (P < 0.05). Therefore, the results of this study do not agree with the previously held view that Q and PFCF increase due to the removal of pain after the elevation operation. It is our contention that comparison of the forces measured preoperatively in a painful joint with the forces that can be attained postoperatively in the pain-free joint can lead to errors in biomechanical evaluations.