27422

Reconstruction of dislocating patella; (e.g., Hauser Type Procedure)

CPT code 27422 describes the surgical procedure for the reconstruction of a dislocating patella, often employing techniques similar to the Hauser type procedure, Elmslie-Trillat procedure, or other soft tissue realignment methods. The patella (kneecap) normally tracks within the trochlear groove of the femur. When this tracking mechanism is disrupted, the patella can dislocate or subluxate, leading to pain, instability, and potential damage to the articular cartilage over time. This procedure aims to stabilize the patella and prevent recurrent episodes of dislocation or subluxation. The underlying cause of patellar instability can be multifactorial, including anatomical variations such as trochlear dysplasia (a shallow femoral groove), patella alta (a high-riding patella), an increased Q-angle (the angle formed by the quadriceps muscle and the patellar tendon), ligamentous laxity, or muscle imbalances. The reconstruction typically involves a combination of soft tissue procedures designed to rebalance the forces acting on the patella. This commonly includes a lateral retinacular release, where the tight lateral structures pulling the patella laterally are incised to reduce lateral tension. Additionally, it often involves a medial patellar plication or advancement of the vastus medialis obliquus (VMO) muscle, a part of the quadriceps, to provide a more effective medial pull and enhance stability. While medial patellofemoral ligament (MPFL) repair or reconstruction using a graft is a distinct procedure (coded as 27427), basic soft tissue tightening or repair of the medial retinaculum as part of a broader realignment may be included in 27422. The specific techniques employed depend on the individual patient's anatomy, the severity and chronicity of instability, and the surgeon's preference. The primary goal is to correct abnormal patellar tracking, reduce excessive lateral pull, and enhance medial stability. This code is specifically for soft tissue procedures and does not encompass bony procedures like tibial tubercle osteotomy (which would typically be coded separately or as part of a more comprehensive code like 27424 if combined with soft tissue repair). The procedure is usually performed under general or regional anesthesia, and postoperative care involves immobilization and a structured physical therapy program to restore strength and range of motion.

Clinical Indications

  • Recurrent patellar dislocations despite adequate conservative management.
  • Chronic patellar instability leading to significant functional limitations and pain.
  • History of multiple patellar subluxations causing symptomatic instability.
  • Evidence of anatomical predisposition to patellar instability (e.g., patella alta, increased Q-angle, mild trochlear dysplasia) in conjunction with instability symptoms, where soft tissue correction is deemed appropriate.
  • Damage to articular cartilage or other intra-articular structures secondary to recurrent instability or maltracking.
  • Failed non-operative treatment for patellar instability (e.g., physical therapy, bracing, activity modification).

Procedure Steps

  1. **Anesthesia and Positioning**: Patient is placed in a supine position; general or regional anesthesia is administered. A tourniquet may be applied to the upper thigh to provide a bloodless field.
  2. **Incision**: A longitudinal or curvilinear incision is made on the medial or anterior aspect of the knee, providing adequate access to the patella and surrounding retinacular structures.
  3. **Lateral Retinacular Release**: The lateral retinaculum, which can be a source of excessive lateral pull on the patella, is identified and incised or released to alleviate lateral tension and allow for more medial tracking.
  4. **Medial Plication/Advancement**: The medial retinaculum and often the vastus medialis obliquus (VMO) muscle are advanced, plicated (folded and sutured), or imbricated to create a stronger medial pull on the patella, thereby enhancing stability. This may involve releasing the VMO from its origin and reattaching it more distally and medially.
  5. **Patellar Tracking Assessment**: The knee is moved through a full range of motion to dynamically assess patellar tracking and ensure adequate stability. Adjustments to the soft tissue repair are made as necessary.
  6. **Hemostasis and Closure**: The surgical site is irrigated, hemostasis is achieved, and the incision is closed in layers (capsule, subcutaneous tissue, skin). A sterile dressing is applied, and a knee immobilizer or brace may be placed to protect the repair.

Coding Guidelines

  • CPT code 27422 specifically describes soft tissue procedures for the reconstruction of a dislocating patella. It includes techniques such as lateral retinacular release, medial patellar plication, or advancement of the vastus medialis obliquus (VMO).
  • This code is distinct from procedures involving bony transfers of the tibial tubercle (e.g., 27420, 27424). If a tibial tubercle osteotomy is performed in conjunction with soft tissue reconstruction, consider CPT code 27424 ('Reconstruction of dislocating patella, with osteotomy of tibial tubercle, medial transfer'), which is a comprehensive code for both bone and soft tissue work. Do not bill 27422 and 27424 together.
  • An isolated Medial Patellofemoral Ligament (MPFL) reconstruction using a graft is typically reported with CPT code 27427. If 27422 is performed alongside an MPFL reconstruction, careful documentation is needed to support the distinctness of the procedures, and modifier 59 may be applicable, though often the more comprehensive or extensive procedure (like 27427) may encompass elements of soft tissue realignment.
  • Diagnostic arthroscopy performed immediately prior to an open procedure like 27422 is generally considered an integral part of the open procedure and is not separately reported. If the arthroscopy addresses a distinct pathology not related to the open procedure, it may be separately billable with modifier 59, supported by clear documentation.
  • Laterality: If the procedure is performed bilaterally, append modifier 50 to CPT code 27422.
  • Check NCCI (National Correct Coding Initiative) edits for bundling rules with other knee procedures if multiple procedures are performed during the same operative session.

Associated ICD-10 Codes