NL Sinvestigation in evaluating the condition of knee joint affected by osteoarthritis deformans

Introduction

 Primary osteoarthritis deformans of the knee joint is one of the most pertinent problems in modern medicine due to its prelevance, great loss of working time and treatment expenses. In addition, in many cases an early or differential diagnosis of the knee joint lesion is impeded, which complicates selecting the most efficient therapeutical and rehabilitation measures and evaluating the patient's disability.

 Today diagnostics of knee joint disorders comprises conventional radiogra phy as well as sonographic evaluation of the joints, used to examine soft tissues of the locomotorium. The existing techniques used to examine the knee joint allow to determine dominance of pathological process in the joint, including degenera tive ones. However, the relationship between the intensity of pathomorphological changes and the severity and dynamics of the process have not been studied yet.

This article aims to demonstrate the efficiency of the NLSinvestigation in diagnosing osteoarthritis deformans, especially in the early (subclinical) phase of the disease.

Subjects and methods

 To define a normal relationship of the knee joint anatomical structures 10 healthy persons aged from 25 to 55 (test group) were examined. The main group consisted of 50 patients with clinical implications of osteoarthritis deformans of knee joints in different phases. The average duration of the dis ease was 7.0±3.0 years. All patients were routinely radiologically examined in two interperpendicular planes

The Xray pattern analysis took into account the joint space amount of narrowing, existence of marginal osteophytes and deformation of osseous structures with cysts and fibrosis areas present in the subcartilaginous bone department. The NLS investigation was carried out using "Oberon" device equipped with a 1.5 GHz trigger sensor. Changes in the joint capsule were evaluat-ed in virtual shots in sagittal planes above and below the kneecap and along the pos terior surface of the joint. Frontal planes along the lateral surfaces of the joint were used to define the exact condition of menisci, articular cartilages and changes in the synovium.

It is traditioanally believed that in the articular cartilage degenerative changes start off with a rupture of the articular matrix and degeneration of chondrosites. Therefore during the NLS examination special attention was paid to changes in the articular cartilage. In the examinees of the test group the articular cartilage looked like a hyperchromous strip (12 points accord ing to the Flandler's scale). Two patients were found to have an articular car tilage of a heterogeneous chromogenic pattern, 35 points, in the initial phase of the disease with small hyperchromogenic nidi (12 points) present. No radiological changes in the joints were detected for this group of patients.

In 14 (28.0%) patients in the second clinical phase of the disease the chromostructure of the cartilage was heterogeneous and some high hyper chromogenic structures (45 points) were detected as well as hyperchro mogenic inclusions (13 points) of a small diameter.

 In 21 (42%) examinees in the third phase of the disease the hyaline car tilage looked as a hyperchromogenic strip (56 points).

 In 10 (20.0%) patients in the same clinical phase of the disease the articu lar cartilage was visualized as a distinctly hyperchromogenic linear structure (6 points) with vertical fissures present (45 points). In three patients the higher line cartilage was not visualized mostly in the middle departments of the joint

 Depending on the phase and duration of the disease a spectral similari ty (D 0.189 to 0.621) could be visualized to the reference standard process 'osteoarthritisdeformans'.

 The Xray pictures detected a moderate constriction and deformity of the joint space as a primary sign of the articular cartilage distraction in 22 patients and considerable constriction in 12 patients. Subcartilaginous osteo phyte was very important for osteoarthritis patagenesis. Formation of subcar tilaginous and epiphyseal sycts started off already in the initial phases of the disease (71.0% of the patients). According to NLSinvestigation, the cysts were located subcartilaginously in the lateral regions of the bone, 1.03.0 mm deep and were as many as 4 to 1215. Standard Xray pictures of knee joints displayed some changes in the subcartilaginousregions of the bone, like cysts and fibrosis, only in the second phase of the disease.

 A very important role in the osteoarthrosis deformans development was attributed to the condition of the synovium and articular capsule. With the progress of the disease and changes in its phases, a cartilaginous detritus with antigenicity was formed on the articular surfaces. That often led to the inflammation of the synovium and its fibrosis. As a result, the synovium pro duced an inadequate fluid, which in turn impaired the cartilagan nutrition with its ensuing degeneration.

 The synovium in healthy persons (test group) was visualized as a hyper chromogenic linear structure (12 points). The first and second phases of the disease saw a steady rise in its chromogenic pattern in 14 (28%) patients (3 4 points). In 32 (62%) patients in the third phase of the disease the chro mogenic density of the membrane reached 45 points throughout the phase with at most 3 or 6 hyperchromogenic inclusions. In three patients with an aggravated form of the osteoarthrosis deformans (the forth clinical phase) the synovium looked like a distinctly hyperchromogenic structure (4 points) with areas of a reduced entropic density (34 points).

 Changes in the membrane structure were always concomitant with syn ovitis with a limited amount (mostly in the upper enstrophe in 28.0% of the patients) or a great amount (in all regions of the joint in 68% of the patients) of fluid free of sediment and additional inclusions.

Depending on the phase and extent of pathological changes in the joint affected by osteoarthrosis a change in the joint capsule structure also took place. Only in the first phase of the disease did the joint capsule structure remain normal.

 In the second phase of the disease, especially with synovitis in evidence, the chromostructure was assessed at 45 points in 14 (28%) patients and in the third and forth phases of the disease up to 6 points in 34 (68%) patients.

 Roentgenographic evidences of synovitis and changes in the paraarticular soft tissues were detected in some patients only in the third and forth phases of the disease.

Thus, the analysis showed that the NLSinvestigation had an advantage over conventional roentgenologic methods in terms of early detection of degenerative changes in the articular cartilage.

On the whole, the NLSmethod sensitivity in the early phase of the dis ease amounted to 82%, specificity to 85% and accuracy to 86%. The sensi tivity of standard radiography in two projections was 68%, specificity 54% and accuracy 78%.

Conclusion

The extensive use of NLSinvestigation of knee joints in everyday clini cal practice allows to diagnose osteoarthrosis deformans in its early phases.