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Official Description

Application of patellar tendon bearing (PTB) cast

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 29435 refers to the application of a patellar tendon bearing (PTB) cast, which is a specialized type of orthopedic cast used primarily for the treatment of stable fractures of the distal tibia. This cast is particularly beneficial as it allows for knee flexion while providing necessary stabilization to the bone during weight-bearing activities. The PTB cast is often utilized as an initial treatment option for such fractures, but it is more commonly employed as a replacement for a long leg cast approximately 4 to 6 weeks after the initial injury. The design of the PTB cast promotes bone healing by facilitating muscular action and intermittent axial compression at the fracture site, which are essential for stimulating bone growth. The application process involves placing the cast in sections over a protective stockinette and minimal padding to ensure comfort and support. The knee is flexed to a right angle during the application, allowing the plaster to be molded flat over the upper calf, creating a triangular cross-section that wraps around the patella while leaving an indentation over the patellar tendon. This specific molding technique is crucial for the cast's effectiveness, as it helps to prevent rotation of the proximal tibia when the patient is weight-bearing. The edges of the cast are carefully trimmed into a wing shape around the femoral condyles, further enhancing stability. Regular follow-up is necessary, with cast changes occurring at 4 to 6-week intervals, and fracture healing can be monitored through X-ray imaging, either with the cast in place or after its removal.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The application of a patellar tendon bearing (PTB) cast is indicated for specific conditions related to the distal tibia. The following are the primary indications for this procedure:

  • Stable Fracture of the Distal Tibia The PTB cast is commonly used as an initial treatment for stable fractures of the distal tibia, providing necessary support and stabilization during the healing process.
  • Replacement of Long Leg Cast After 4 to 6 weeks following a distal tibial injury, the PTB cast may replace a long leg cast, allowing for increased mobility and knee flexion while still ensuring adequate support for the healing bone.

2. Procedure

The procedure for applying a patellar tendon bearing (PTB) cast involves several detailed steps to ensure proper fit and function. Each step is crucial for the effectiveness of the cast in stabilizing the fracture while allowing for knee movement.

  • Preparation of the Limb The first step involves preparing the limb by placing a protective stockinette over the skin, followed by minimal padding to provide comfort and prevent skin irritation. This preparation is essential to create a suitable base for the cast application.
  • Positioning the Knee The patient’s knee is flexed to a right angle, which is critical for the proper molding of the cast. This position allows for optimal support of the knee joint while ensuring that the cast can accommodate movement.
  • Molding the Plaster Plaster is then applied and firmly molded flat over the upper calf, creating a triangular cross-section. This molding is done carefully to ensure that the cast conforms to the anatomy of the leg and provides adequate support.
  • Wrapping Around the Patella The plaster is continued anteriorly around the patella, leaving an indentation over the patellar tendon. This design is intentional, as it allows for knee flexion while maintaining stability at the fracture site.
  • Trimming the Edges After the plaster has set, the edges of the cast are trimmed to create a wing shape around the femoral condyles. This specific shaping is important to prevent rotation of the proximal tibia during weight-bearing activities, which could compromise the healing process.
  • Monitoring and Follow-Up The cast is typically changed at 4 to 6-week intervals, allowing for monitoring of fracture healing. X-ray imaging may be utilized to assess fracture union, either with the cast in place or after its removal, ensuring that the healing process is on track.

3. Post-Procedure

Post-procedure care for a patient with a patellar tendon bearing (PTB) cast includes regular follow-up appointments to monitor the healing of the fracture. The cast is changed at intervals of 4 to 6 weeks, during which the physician will assess the condition of the fracture and the integrity of the cast. Patients are advised to report any signs of complications, such as increased pain, swelling, or changes in sensation in the limb. Additionally, patients should be educated on the importance of weight-bearing as tolerated, as this activity can stimulate bone growth and aid in recovery. Proper care of the cast is also essential to prevent moisture accumulation and skin irritation, which can lead to complications. Overall, adherence to follow-up schedules and monitoring is crucial for successful recovery and fracture healing.

Short Descr APPLY SHORT LEG CAST
Medium Descr APPLICATION PATELLAR TENDON BEARING CAST
Long Descr Application of patellar tendon bearing (PTB) cast
Status Code Active Code
Global Days 000 - Endoscopic or Minor Procedure
PC/TC Indicator (26, TC) 0 - Physician Service Code
Multiple Procedures (51) 2 - Standard payment adjustment rules for multiple procedures apply.
Bilateral Surgery (50) 1 - 150% payment adjustment for bilateral procedures applies.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 1 - Statutory payment restriction for assistants at surgery applies to this procedure...
Co-Surgeons (62) 0 - Co-surgeons not permitted for this procedure.
Team Surgery (66) 0 - Team surgeons not permitted for this procedure.
Diagnostic Imaging Family 99 - Concept Does Not Apply
APC Status Indicator Procedure or Service, Multiple Reduction Applies
ASC Payment Indicator Office-based surgical procedure added to ASC list in CY 2008 or later with MPFS nonfacility PE RVUs; payment based on MPFS nonfacility PE RVUs.
Type of Service (TOS) 2 - Surgery
Berenson-Eggers TOS (BETOS) P6B - Minor procedures - musculoskeletal
MUE 1
CCS Clinical Classification 214 - Traction, splints, and other wound care
58 Staged or related procedure or service by the same physician or other qualified health care professional during the postoperative period: it may be necessary to indicate that the performance of a procedure or service during the postoperative period was: (a) planned or anticipated (staged); (b) more extensive than the original procedure; or (c) for therapy following a surgical procedure. this circumstance may be reported by adding modifier 58 to the staged or related procedure. note: for treatment of a problem that requires a return to the operating/procedure room (eg, unanticipated clinical condition), see modifier 78.
59 Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
GW Service not related to the hospice patient's terminal condition
LT Left side (used to identify procedures performed on the left side of the body)
RT Right side (used to identify procedures performed on the right side of the body)
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