Gonalgia, fatigue with ambulation and inability to run. These symptoms have increased since birth.
The patient presents with arthrogryposis. She complains of gonalgia, fatigue with ambulation and inability to run. At birth, the patient did not present any neurosensorial alteration, however, neuromotor responses were altered by generalized articular changes. At birth, her presentation included: head bended on the right shoulder; raised clavicle with limited functionality of the scapulo-humeral joint; decreased mobility of the ribs; reduced passive mobility of bilateral wrists; fingers in semiflexion; limited abduction of the hips; limited flexion of the knees and scissoring of the limbs.
Nowadays, musculoskeletal MRI further showed hypotrophy of muscles of the thigh replaced with fat tissue (figs.1b, 1c) and abnormal shape of menisci and femoral condyles (fig. 1a). Cartilages are thick (fig. 1a, 1d), ligaments abnormally thin (fig. 1c). Patella is partially out of joint (fig. 1a).
Currently, she undergoes physiotherapy and practices swimming.
The term "arthrogryposis” stands for a very heterogeneous group of disorders encompassing multiple congenital muscular contractures [2, 4]. The main cause is fetal akinesia (reduction of fetal movements) caused by fetal diseases [2, 3, 4]. These fetal diseases causes are most commonly neurogenic (i.e. meningomyelocele, spinal muscular atrophy); musculoskeletal (i.e. congenital muscular dystrophies); connective tissue disorders; oligohydramnios (for the pressure on the fetus), or by maternal diseases (infections, drugs, vascular pathologies).
Fetal movements are important for the normal growth of fetal joints and their related structures. In the USA, the frequency of arthrogryposis is 1:3000 live-births. There are no differences in incidence amongst races. Diagnosis is made at birth or in utero with ultrasonography [2].
Not many previous studies have concentrated on the knee abnormalities and their associated radiographic findings: a paper by Guidera K.J. et al. (1991) [1], based on 62 patients with arthrogryposis multiplex congenital, noticed that patellar abnormalities are the most common, above all elongation in patients with long standing flexion contractures. Patella may be alta (fig. 1a) or baja, hypoplastic or absent, perhaps secondary to the lack of developmental stimulus from an incongruous and stiff joint. The proximal or (more frequently) distal patellar pole may be fractured. Patellar subluxation is rare and due to the contracture of the capsule. Bone irregularities are frequently represented by flattened femoral condyle (fig. 1a) and tibial plateau. Fracture is often associated with osteoporosis after casting or surgery. There may be valgus deformity of the knee. Increased radiographical soft-tissue density reflects the thickened nature of joint capsules. In other words, radiographic evaluation demonstrates the marked molding effect secondary to abnormal placement or pressure on the femur, tibia and patella in the arthropgrypotic knee.
Radiographic findings are consistent with the degree of long standing physical deformity and can be used as a guide to the severity of the condition and the need for treatment. Arthrogryposis typically involves the musculoskeletal system but may affect other organ systems. Involved muscles are typically hypoplastic and replaced by fibrous and fat tissue, as seen in our case study (figs. 1b, 1c). Malformations can be present, including craniofacial changes (i.e. micrognathia, palatoschisis, hypertelorism), shortened limbs, absence of patella, radial luxation, scoliosis, genital deformities, inguinal or umbilical hernia, short bowel, pulmonary hypoplasia.
Intelligence is normal [2,3].
Life expectancy is usually not affected. The seriousness of the disease or the presence of severe malformations may impact the overall outcome of the patient.
Laboratory tests aren’t very useful except CPK when there is muscular involvement with reduced muscular masses and weakness. Muscular biopsy is probably the most important diagnostic procedure and electromyography can differentiate neurogenic causes from myopathic ones.
Medical therapy consists in a vigorous physiotherapy to reduce contractures and to avoid muscular atrophy.
Surgical therapy for soft tissues should be done early, while osteotomies delayed until growth is completed [2].
Arthrogryposis of the knee
Based on the provided Magnetic Resonance Imaging (MRI) images and the patient's clinical history, the following main features can be observed:
1. Abnormal knee joint structure: Some images show irregular patellar morphology or suggest an abnormal patellar position (e.g., patella alta or patella baja), and signs of joint surface dysplasia.
2. Changes in bone morphology: There may be a certain degree of flattening of the femoral condyle and tibial plateau, indicating long-term abnormal stress or developmental dysplasia.
3. Muscular atrophy: Reduced muscle volume in the thigh and calf; some soft tissue signals suggest possible fibrous and fatty replacement, consistent with long-term insufficient muscle strength or myopathic changes.
4. Joint capsule and surrounding soft tissues: Thickening of the joint capsule and increased soft tissue density, suggesting hyperplasia and contracture possibly caused by long-term immobility or deformity-related traction.
Overall, the imaging findings are consistent with long-term muscle weakness, reduced joint activity, and developmental anomalies.
Given the patient’s lower extremity dysfunction since birth (walking difficulty, poor running ability), knee joint pain, and the aforementioned imaging findings, the following diagnoses or differential diagnoses should be considered:
1. Arthrogryposis Multiplex Congenita (AMC)
• Characterized by multiple joint contractures present at birth, commonly with poor muscle development or fibrofatty replacement.
• The knee joint often shows abnormal patellar shape or position, flattened bone surfaces, and significant joint capsule thickening.
2. Congenital Patellar Dysplasia (e.g., congenital patellar dislocation, patella alta/baja, etc.)
• May present with patellar dysplasia or displacement, often involving the patella itself, sometimes accompanied by femoral trochlear dysplasia.
• If there is no involvement of multiple joints or other systemic manifestations, it does not fully match the long-term multi-joint symptoms in this case.
3. Other Congenital Musculoskeletal Disorders (e.g., congenital muscular dystrophy, neurogenic disorders, etc.)
• May present with similar muscle weakness and limited joint mobility but often accompanied by varying degrees of neurological or specific muscle gene defects, necessitating further differentiation with electromyography, genetic testing, or muscle biopsy.
Considering the patient's long-term knee pain, soft tissue contracture, poor muscle strength, and MRI findings showing abnormal patellar and bone morphology, joint capsule thickening, and fibrofatty replacement in muscles, the most likely diagnosis is: Arthrogryposis Multiplex Congenita (AMC).
Given the clear clinical presentation and imaging changes, if there is still uncertainty, electromyography, muscle biopsy, or further genetic testing can be performed to clarify the underlying cause (neurogenic or myogenic).
1. Overview of Treatment Measures
• Conservative treatment: Includes active physical therapy and rehabilitation training aimed at reducing joint contractures and maintaining muscle strength; for significant pain, consider analgesics or protective braces for the joints.
• Surgical treatment: If deformities severely affect function or if there is significant knee pain and structural abnormalities, consider soft tissue release, tendon transfer, joint release, or osteotomy. Surgical intervention on bone is generally performed after skeletal maturity to minimize effects on bone development.
2. Recommendations for Rehabilitation/Exercise Prescription (FITT-VP Principle)
• Frequency: Rehabilitation training can be performed 3–5 times per week, adjusted according to joint tolerance.
• Intensity: Begin with a low intensity that does not cause significant pain or excessive fatigue; focus on light to moderate resistance training and joint range of motion exercises.
• Time: Each rehabilitation session should last 15–30 minutes, possibly split into segments to prevent excessive fatigue. Gradually extend to 45 minutes or more as tolerated.
• Type:
1) Range of motion exercises: Such as passive stretching and active joint movement exercises, with a focus on maintaining and improving knee flexion and extension.
2) Strength training: Use elastic bands or light weights to train the quadriceps and hamstrings; if joint stability is poor, braces may be used under professional guidance.
3) Aerobic exercise: Consider arm ergometer or aquatic exercises to reduce weight-bearing stress on the knees.
• Progression: Gradually increase training resistance or load as muscle strength and joint range of motion improve, while monitoring pain and joint stability.
3. Special Precautions
• Owing to long-term deformities and muscle atrophy, bone quality may be relatively fragile. Avoid excessive or rapid joint impact.
• If there is joint swelling, severe pain, or other discomfort, suspend training and seek medical evaluation promptly.
• Regularly follow up with imaging and muscle strength assessments to adjust the rehabilitation plan in a timely manner.
This report is a reference analysis based on provided information and cannot replace an in-person consultation or professional medical diagnosis and treatment advice. Specific treatment plans should be conducted under the guidance of a specialist to ensure safety and effectiveness.
Arthrogryposis of the knee
