Elbow Varus: Understanding Cubitus Varus and Gunstock Deformity, Causes, Symptoms, and Treatment

What is elbow varus called?

Elbow varus, a condition where the forearm deviates inward towards the midline of the body, is medically termed cubitus varus and is also commonly known as gunstock deformity due to its characteristic appearance.

Understanding Elbow Varus: Definition and Anatomy

The human elbow joint is a complex hinge joint formed by the distal end of the humerus (upper arm bone) and the proximal ends of the radius and ulna (forearm bones). In a healthy individual, when the arm is extended and supinated (palm facing forward), the forearm typically deviates slightly outward from the midline of the body, creating what is known as the "carrying angle." This normal outward angulation is called cubitus valgus, and it averages about 10-15 degrees in adults.

Elbow varus, in contrast, describes an abnormal inward angulation of the forearm relative to the humerus when the arm is extended. Instead of the forearm angling slightly away from the body, it angles towards or even past the midline, creating a visual deformity. This deviation disrupts the natural biomechanics of the joint and can have functional implications.

What is Cubitus Varus? The Primary Term

The most accurate and widely accepted medical term for elbow varus is cubitus varus.

• "Cubitus" refers to the forearm or elbow region.
• "Varus" is a Latin term used in anatomy and medicine to describe an angulation of a distal segment of a limb towards the midline of the body. This is in contrast to "valgus," which describes angulation away from the midline.

Therefore, cubitus varus directly translates to an inward angulation of the forearm at the elbow joint. This term is preferred in clinical and academic settings for its precision.

The "Gunstock Deformity" Explained

Beyond its medical nomenclature, cubitus varus is also colloquially and descriptively known as gunstock deformity. This descriptive term arises from the characteristic appearance of the affected arm: when the elbow is extended, the inward angulation of the forearm resembles the shape of a rifle stock. While not a formal medical diagnosis, "gunstock deformity" is a widely recognized and useful descriptor for the visual manifestation of cubitus varus.

Causes of Elbow Varus

The vast majority of cubitus varus cases are acquired, meaning they develop after birth, primarily due to trauma.

• Malunion of Supracondylar Humerus Fractures: This is by far the most common cause, especially in children. A supracondylar humerus fracture occurs just above the elbow joint. If this fracture heals improperly (malunion), particularly with rotational or angular displacement, it can lead to the development of cubitus varus. The growth plates in children are particularly vulnerable, and improper alignment during healing can alter future bone growth.
• Physeal Injuries: Injuries to the growth plates (physes) around the elbow in children can lead to premature closure or asymmetric growth, resulting in angular deformities like varus.
• Congenital Conditions: Rarely, cubitus varus can be present at birth due to developmental abnormalities.
• Infection or Tumors: In very rare instances, conditions like osteomyelitis or benign/malignant bone tumors affecting the distal humerus can lead to bone deformities that result in cubitus varus.

Symptoms and Functional Impact

While primarily a cosmetic concern for many, cubitus varus can also lead to functional issues and long-term complications.

• Cosmetic Deformity: The most obvious symptom is the visible inward angulation of the forearm, which can be particularly noticeable when the arm is extended.
• Altered Biomechanics: The abnormal alignment changes the forces transmitted through the elbow joint and surrounding structures. This can lead to:
  • Decreased Range of Motion (ROM): While often not severely limited, some individuals may experience subtle restrictions in full extension or flexion, or altered pronation/supination.
  • Muscle Imbalances: Compensatory muscle activity can develop to adapt to the altered joint mechanics.
• Tardy Ulnar Nerve Palsy: This is a significant long-term complication. The ulnar nerve runs behind the medial epicondyle of the humerus (the "funny bone"). In cubitus varus, the altered bony alignment can stretch or compress the ulnar nerve over time, leading to:
  • Numbness and tingling in the little finger and half of the ring finger.
  • Weakness in hand intrinsic muscles.
  • Eventually, muscle wasting and clawing of the hand. Symptoms may not appear until years or even decades after the initial injury.
• Elbow Instability or Arthritis: The abnormal loading patterns on the joint can predispose it to early degenerative changes (osteoarthritis) or, less commonly, instability.

Diagnosis of Elbow Varus

Diagnosis typically involves a combination of clinical examination and imaging:

• Clinical Examination: A physical assessment by a healthcare professional will involve visual inspection of the arm, measurement of the carrying angle (often using a goniometer), and assessment of elbow range of motion, stability, and neurological function (especially ulnar nerve integrity).
• Radiographs (X-rays): Standard anteroposterior (AP) and lateral X-rays of the elbow are essential. These images allow for precise measurement of the varus deformity and help identify the underlying bony malunion or growth plate abnormalities. Specific angles and lines (e.g., Baumann's angle) are used to quantify the deformity.
• CT Scans or MRI: In complex cases, or if detailed assessment of bone rotation or soft tissue structures (like the ulnar nerve) is required, a CT scan or MRI may be utilized.

Treatment and Management Strategies

The treatment approach for cubitus varus depends on the severity of the deformity, the presence of symptoms (especially ulnar nerve involvement), and the patient's age.

• Non-Surgical Management: For mild, asymptomatic cases, especially if the deformity is purely cosmetic and not causing functional issues or nerve symptoms, a non-surgical approach may be adopted. This typically involves observation and monitoring for any progression of symptoms. Physical therapy may be recommended to maintain range of motion and strength, but it cannot correct the bony deformity itself.
• Surgical Correction (Corrective Osteotomy): For significant deformities, functional limitations, or the presence of ulnar nerve symptoms, surgical correction is the primary treatment.
  • Supracondylar Osteotomy: This is the most common procedure. It involves cutting the humerus bone just above the elbow joint, realigning it to correct the varus angulation and restore a more normal carrying angle, and then fixing the bone in the corrected position with plates, screws, or pins.
  • Ulnar Nerve Transposition: If ulnar nerve compression or symptoms are present, a procedure to move the ulnar nerve to a less vulnerable position (anterior transposition) may be performed concurrently or as a separate procedure.

Rehabilitation and Long-Term Outlook

Following surgical correction, rehabilitation is crucial for optimal recovery.

• Post-Operative Immobilization: The elbow will typically be immobilized in a cast or brace for several weeks to allow bone healing.
• Physical Therapy: Once the bone has healed sufficiently, a progressive physical therapy program will be initiated. This focuses on:
  • Restoring full elbow range of motion (flexion, extension, pronation, supination).
  • Strengthening the muscles around the elbow, shoulder, and hand.
  • Addressing any residual stiffness or weakness.
  • Neuromuscular re-education. The long-term outlook after corrective osteotomy is generally good, with significant improvement in cosmetic appearance and often resolution of functional limitations or ulnar nerve symptoms. However, some individuals may experience minor residual stiffness or the potential for late-onset osteoarthritis if the joint mechanics remain subtly altered.

Preventative Measures and Considerations for Athletes/Trainers

For fitness enthusiasts, personal trainers, and student kinesiologists, understanding cubitus varus is important for both recognition and appropriate guidance:

• Proper Fracture Management: The most effective "prevention" of cubitus varus lies in the accurate and timely management of supracondylar humerus fractures, especially in children. Ensuring proper reduction (alignment) and immobilization of these fractures is paramount.
• Early Recognition of Deformity: Trainers working with young athletes or individuals with a history of elbow trauma should be aware of the signs of cubitus varus. A noticeable inward angulation of the forearm or any complaints of numbness/tingling in the hand, or progressive weakness, warrant immediate medical referral.
• Biomechanics and Exercise Selection: For individuals with existing cubitus varus (even if asymptomatic), understanding the altered biomechanics is key. The changed carrying angle can affect the alignment of the shoulder and wrist during certain movements. Exercises that place undue stress on the elbow joint or potentially irritate the ulnar nerve (e.g., deep triceps extensions, certain pressing movements) might need modification or avoidance.
• Referral to Medical Professionals: It is critical for fitness professionals to recognize their scope of practice. Any suspicion of cubitus varus, or if a client reports symptoms consistent with ulnar nerve irritation, requires immediate referral to an orthopedic surgeon or sports medicine physician for proper diagnosis and management. Attempting to "correct" a bony deformity through exercise is not possible and can be harmful.

Conclusion

Elbow varus, medically known as cubitus varus and descriptively as gunstock deformity, is an inward angulation of the forearm at the elbow joint, most commonly resulting from malunion of a childhood supracondylar humerus fracture. While often a cosmetic concern, it can lead to significant functional limitations and neurological complications like tardy ulnar nerve palsy. Diagnosis relies on clinical examination and X-rays, with surgical osteotomy being the primary treatment for symptomatic or severe cases. Understanding this condition is vital for healthcare and fitness professionals to ensure appropriate recognition, referral, and management.