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Official Description

Disarticulation at knee

© Copyright 2025 American Medical Association. All rights reserved.

Common Language Description

The procedure described by CPT® Code 27598 refers to a disarticulation at the knee, which is a surgical operation involving the complete removal of the leg at the knee joint. This procedure is typically indicated in cases where there is severe trauma, infection, or other medical conditions that necessitate the amputation of the leg at this specific joint. The surgical technique involves creating a fish-mouth incision, which is a specific type of incision that allows for the effective removal of the leg while preserving as much surrounding tissue as possible for optimal healing and prosthetic fitting. The anterior flap is designed to extend approximately 4 inches distal to the knee joint, while the posterior flap extends about 1.5 inches distal to the joint, ensuring adequate coverage and closure post-surgery. The procedure requires careful dissection of the skin down to the deep fascia, followed by the reflection of the flaps to expose the knee joint and surrounding structures. The surgical steps involve the division of key anatomical structures, including the patellar tendon, joint capsule, ligaments, and blood vessels, which are essential for the successful execution of the disarticulation. The meticulous approach taken during this procedure aims to minimize complications and promote effective recovery for the patient.

© Copyright 2025 Coding Ahead. All rights reserved.

1. Indications

The disarticulation at the knee, as described by CPT® Code 27598, is performed under specific clinical circumstances. The following indications may warrant this surgical intervention:

  • Severe Trauma: Cases of significant injury to the leg that cannot be repaired or salvaged may necessitate disarticulation at the knee.
  • Infection: Persistent or severe infections in the lower leg that do not respond to conservative treatment may require amputation to prevent systemic complications.
  • Malignancy: Tumors located in the knee joint or surrounding tissues that compromise the integrity of the leg may lead to the decision for disarticulation.
  • Vascular Disease: Conditions such as critical limb ischemia, where blood flow is severely compromised, may result in the need for amputation to alleviate pain and prevent further complications.

2. Procedure

The procedure for disarticulation at the knee involves several critical steps to ensure a successful outcome. Each step is performed with precision to minimize complications and promote healing.

  • Step 1: A fish-mouth incision is marked on the skin, with an anterior flap extending approximately 4 inches distal to the knee joint and a posterior flap extending about 1.5 inches distal to the joint. This incision design is crucial for adequate exposure and closure.
  • Step 2: The skin is incised down to the deep fascia, which is then carefully dissected off the joint capsule to expose the underlying structures.
  • Step 3: The flaps are reflected upward above the level of the femoral condyle, allowing for better access to the knee joint and surrounding tissues.
  • Step 4: The patellar tendon is divided, which is essential for the subsequent steps of the procedure.
  • Step 5: The knee is flexed to facilitate the severing of the joint capsule and surrounding ligaments, which are critical for the disarticulation process.
  • Step 6: The popliteal vessels are suture ligated and divided to control bleeding and ensure proper management of vascular structures during the procedure.
  • Step 7: The popliteal nerve is divided to prevent any potential nerve-related complications post-surgery.
  • Step 8: The hamstrings are detached, and the patella is dissected from the patellar tendon and removed, completing the disarticulation of the leg.
  • Step 9: Once all connective tissue has been divided, the lower leg is removed, marking the completion of the disarticulation.
  • Step 10: The medial and lateral femoral condyles are partially removed, and the corners are smoothed using a rasp to prepare the site for closure.
  • Step 11: Any protrusions on the posterior surface of the femur are smoothed using an osteotome, ensuring a clean and even surface.
  • Step 12: The hamstrings and patellar tendon are sutured together over the intercondylar notch to provide stability to the surgical site.
  • Step 13: Drains are placed to prevent fluid accumulation and promote healing.
  • Step 14: The flaps are aligned, and the deep fascia and skin are closed in layers around the drains to ensure proper healing and minimize scarring.
  • Step 15: A compression dressing is applied to support the surgical site and reduce swelling.

3. Post-Procedure

After the disarticulation at the knee, patients will require careful monitoring and post-operative care. Expected recovery includes managing pain, preventing infection, and monitoring the surgical site for any complications. Patients may need physical therapy to adapt to the changes and to prepare for potential prosthetic fitting. Follow-up appointments are essential to assess healing and to address any concerns that may arise during the recovery process. The application of a compression dressing will help in reducing swelling and supporting the surgical area as it heals.

Short Descr AMPUTATE LOWER LEG AT KNEE
Medium Descr DISARTICULATION KNEE
Long Descr Disarticulation at knee
Status Code Active Code
Global Days 090 - Major Surgery
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) 2 - Payment restriction for assistants at surgery does not apply to this procedure...
Co-Surgeons (62) 1 - Co-surgeons could be paid, though supporting documentation is required...
Team Surgery (66) 0 - Team surgeons not permitted for this procedure.
Diagnostic Imaging Family 99 - Concept Does Not Apply
APC Status Indicator Inpatient Procedures, not paid under OPPS
Type of Service (TOS) 2 - Surgery
Berenson-Eggers TOS (BETOS) P3D - Major procedure, orthopedic - other
MUE 1
CCS Clinical Classification 157 - Amputation of lower extremity
22 Increased procedural services: when the work required to provide a service is substantially greater than typically required, it may be identified by adding modifier 22 to the usual procedure code. documentation must support the substantial additional work and the reason for the additional work (ie, increased intensity, time, technical difficulty of procedure, severity of patient's condition, physical and mental effort required). note: this modifier should not be appended to an e/m service.
50 Bilateral procedure: unless otherwise identified in the listings, bilateral procedures that are performed at the same session, should be identified by adding modifier 50 to the appropriate 5 digit code. note: this modifier should not be appended to designated "add-on" codes (see appendix d).
51 Multiple procedures: when multiple procedures, other than e/m services, physical medicine and rehabilitation services or provision of supplies (eg, vaccines), are performed at the same session by the same individual, the primary procedure or service may be reported as listed. the additional procedure(s) or service(s) may be identified by appending modifier 51 to the additional procedure or service code(s). note: this modifier should not be appended to designated "add-on" codes (see appendix d).
52 Reduced services: under certain circumstances a service or procedure is partially reduced or eliminated at the discretion of the physician or other qualified health care professional. under these circumstances the service provided can be identified by its usual procedure number and the addition of modifier 52, signifying that the service is reduced. this provides a means of reporting reduced services without disturbing the identification of the basic service. note: for hospital outpatient reporting of a previously scheduled procedure/service that is partially reduced or cancelled as a result of extenuating circumstances or those that threaten the well-being of the patient prior to or after administration of anesthesia, see modifiers 73 and 74 (see modifiers approved for asc hospital outpatient use).
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.
62 Two surgeons: when 2 surgeons work together as primary surgeons performing distinct part(s) of a procedure, each surgeon should report his/her distinct operative work by adding modifier 62 to the procedure code and any associated add-on code(s) for that procedure as long as both surgeons continue to work together as primary surgeons. each surgeon should report the co-surgery once using the same procedure code. if additional procedure(s) (including add-on procedure(s) are performed during the same surgical session, separate code(s) may also be reported with modifier 62 added. note: if a co-surgeon acts as an assistant in the performance of additional procedure(s), other than those reported with the modifier 62, during the same surgical session, those services may be reported using separate procedure code(s) with modifier 80 or modifier 82 added, as appropriate.
78 Unplanned return to the operating/procedure room by the same physician or other qualified health care professional following initial procedure for a related procedure during the postoperative period: it may be necessary to indicate that another procedure was performed during the postoperative period of the initial procedure (unplanned procedure following initial procedure). when this procedure is related to the first, and requires the use of an operating/procedure room, it may be reported by adding modifier 78 to the related procedure. (for repeat procedures, see modifier 76.)
79 Unrelated procedure or service by the same physician or other qualified health care professional during the postoperative period: the individual may need to indicate that the performance of a procedure or service during the postoperative period was unrelated to the original procedure. this circumstance may be reported by using modifier 79. (for repeat procedures on the same day, see modifier 76.)
80 Assistant surgeon: surgical assistant services may be identified by adding modifier 80 to the usual procedure number(s).
82 Assistant surgeon (when qualified resident surgeon not available): the unavailability of a qualified resident surgeon is a prerequisite for use of modifier 82 appended to the usual procedure code number(s).
AS Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery
CR Catastrophe/disaster related
GC This service has been performed in part by a resident under the direction of a teaching physician
GV Attending physician not employed or paid under arrangement by the patient's hospice provider
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)
XP Separate practitioner, a service that is distinct because it was performed by a different practitioner
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