The medial collateral ligament (MCL) consists of superficial and deep fibers that originate from the medial epicondyle of the femur and insert onto the medial surface of the tibia. In hemophilic arthropathy, this ligament undergoes significant structural alterations due to chronic capsular distension and repeated inflammatory episodes that compromise the integrity of collagen fibers.

Characteristic: Length: 8–10 cm, thickness of superficial fibers: 5–7 mm

Findings:

• Chronic thickening: Increased thickness of the superficial fibers with loss of normal stratification.
• Ligamentous calcifications: Linear calcific deposits along the fiber course, particularly at the insertions.
• Interstitial edema: Hypoechoic intraligamentous areas due to recurrent inflammatory processes.
• Secondary laxity: Fiber elongation with loss of normal tension, contributing to joint instability.

Probe Positioning
Place the probe longitudinally over the medial femoral epicondyle, following the ligament course down to the proximal tibia. The probe marker should be oriented cranially. Minimal pressure should be applied to avoid compressing the superficial structures.

The medial meniscus has a more closed “C” shape compared to the lateral one and is closely connected to the joint capsule and the medial collateral ligament. In hemophilic arthropathy, this structure is particularly vulnerable to degenerative changes due to its reduced mobility and greater exposure to mechanical stress.

Characteristic: Shape: Closed C-shape, extensive capsular adhesions

Findings:

• Early myxoid degeneration: Diffuse increase in echogenicity with loss of the normal triangular morphology.
• Stress lesions: Longitudinal and radial fissures due to altered joint biomechanics.
• Meniscal calcifications: Intraradical calcific deposits, particularly in the posterior horn.
• Pathological extrusion: Protrusion beyond the tibial margins associated with MCL laxity and capsular alterations.

Probe Positioning
Perform transverse and longitudinal scanning at the level of the medial joint line. The probe should be placed just posterior to the medial collateral ligament, with optimization through valgus stress and flexion-extension movements.

The pes anserinus represents the common insertional convergence of the sartorius, gracilis, and semitendinosus tendons on the anteromedial surface of the proximal tibia. In hemophilic arthropathy, this region may develop chronic inflammatory changes due to functional compensations and postural alterations secondary to joint disease.

Characteristic: Common insertion: 4–6 cm below the joint line, anteromedial surface of the tibia

Findings:

• Reactive tendinopathy: Tendon thickening with altered echotexture due to compensatory overload.
• Chronic anserine bursitis: Thickening of the bursal walls with possible parietal calcifications.
• Scar adhesions: Loss of gliding planes between the tendons and adjacent structures.
• Insertional enthesopathy: Tibial insertion changes with irregular bone profile and possible erosions.

Probe Positioning
Place the probe longitudinally and transversely on the anteromedial surface of the proximal tibia, 4–6 cm below the joint line, where the sartorius, gracilis, and semitendinosus tendons converge.