What Are Common Orthopedic Surgeries for Morquio?

Individuals with Mucopolysaccharidosis type 4 (Morquio syndrome) frequently experience significant skeletal abnormalities as part of their condition. Beyond the spine, the hips and knees are the most commonly affected areas. The primary goal of lower-extremity orthopedic surgeries is to reduce joint pain and help you or your child maintain the ability to walk and stay active. Because of how Morquio affects bone growth, these procedures focus on correcting alignment and stabilizing joints.

Hip Surgeries: Managing Dysplasia and Arthritis

Hip dysplasia, where the hip socket does not fully cover the ball of the upper thigh bone, is very common in Morquio syndrome. Over time, this can lead to instability, dislocation, or early arthritis ^[1][2].

• Pre-Surgical Testing (Arthrography): Because the hip joint in Morquio can be uniquely malformed, specialists strongly recommend dynamic testing, such as an arthrogram (an X-ray taken after injecting dye into the joint). This helps the surgeon understand how the hip functions while moving and determines the best surgical approach ^[3][4].
• Osteotomies (Bone Re-shaping): Depending on the results of the arthrogram, surgeons may perform a pelvic osteotomy (reshaping the hip socket to better cover the femoral head) or a femoral osteotomy (re-angling the top of the thigh bone to fit better into the socket) ^[4]. These procedures aim to improve how the joint fits together, reducing pain and preventing further damage.
• Total Hip Arthroplasty (Hip Replacement): Surgeons typically try to delay joint replacement until the patient is older. However, in cases where the hip has developed severe arthritis or significant soft tissue contractures, a total hip replacement might be necessary, even at a young age ^[2]. Because patients with Morquio often have poor bone quality, surgeons typically use cemented implants to ensure the new joint is securely fixed in place ^[5].

Knee Surgeries: Correcting Knock-Knees (Genu Valgum)

Many children with Morquio develop severe knock-knees, medically known as genu valgum. As the child grows into a teen and adult, the uneven weight distribution on the knees can make walking difficult and painful.

• Guided Growth (Hemiepiphysiodesis): This is the most common and preferred treatment for knock-knees in growing children ^[6][7][8]. The surgeon places a small metal plate on one side of the growth plate near the knee. This temporarily tethers the growth on that side, allowing the other side to catch up and gradually straighten the leg over time. It is a highly successful and less invasive procedure, but it works best if performed early—ideally before the angle of the knee exceeds 20 degrees ^[6]. The patient must be closely monitored to ensure the leg does not overcorrect, especially after the plates are removed ^[9][10].
• Corrective Osteotomy: If the knock-knees are too severe (past 20 degrees) or if the patient has finished growing, guided growth is no longer an option ^[6][11]. In these cases, a distal femoral osteotomy may be necessary ^[12][13]. This involves cutting the bone near the knee, straightening it into the correct position, and holding it in place with plates and screws while it heals.

Recovery and Rehabilitation

Recovery from these procedures requires patience and coordination with a physical therapy team. While guided growth procedures are less invasive and usually involve a quicker recovery, more complex surgeries like osteotomies or joint replacements may require weeks of limited weight-bearing. You may need to plan for the temporary use of mobility aids, such as a wheelchair or walker, and commit to physical therapy to regain strength and flexibility after surgery.

Surgical Precautions in Morquio Syndrome

While these lower-extremity surgeries are crucial for mobility, any operation requiring anesthesia carries higher risks for individuals with Morquio syndrome ^[5].

• Anesthesia Risks: Airway narrowing and heart issues are common, meaning a specialized pediatric anesthesiologist experienced with MPS is critical for safely managing the patient during surgery and recovery ^[5].
• Spinal Protection: Even during leg or hip surgeries, the patient’s neck must be carefully positioned and protected due to the high risk of cervical spine instability. Surgeons often use intraoperative neuromonitoring (IONM) to monitor spinal cord function while the patient is asleep ^[12].