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Official Description

Arthrotomy, knee, with exploration, drainage, or removal of foreign body (eg, infection)

© Copyright 2025 American Medical Association. All rights reserved.

Common Language Description

The procedure described by CPT® Code 27310 refers to an arthrotomy of the knee, which is a surgical intervention involving a skin incision made over the knee joint. This procedure is performed to explore the joint, drain any accumulated fluid, or remove foreign bodies, particularly in cases where an infection is present. The term 'arthrotomy' specifically denotes the surgical opening of a joint, allowing for direct access to the internal structures of the knee. During the procedure, the surgeon dissects through the surrounding tissues to expose the joint capsule, which is then opened to facilitate exploration of the knee joint itself. If an infection is identified, the surgeon will drain fluid that may contain blood and pus, which is indicative of an infectious process. Additionally, cultures are obtained from the joint fluid for laboratory analysis, which is essential for identifying the causative organism and guiding appropriate treatment. The knee joint is thoroughly flushed with saline solution to clear any debris and ensure a clean environment for healing. Any foreign bodies present within the joint are carefully located and removed. After the necessary interventions, the knee is flushed again with saline to ensure all contaminants are cleared. Depending on the extent of the procedure and the condition of the joint, drains may be placed to facilitate fluid drainage post-operatively. Finally, the incision is closed in layers around the drain, and a dressing is applied to protect the surgical site during the recovery process.

© Copyright 2025 Coding Ahead. All rights reserved.

1. Indications

The procedure described by CPT® Code 27310 is indicated for various conditions affecting the knee joint, particularly when there is a suspicion of infection or the presence of foreign bodies. The following are specific indications for performing an arthrotomy of the knee:

  • Infection: The procedure is indicated when there is evidence of infection within the knee joint, which may present as swelling, pain, and the presence of purulent fluid.
  • Foreign Body Presence: An arthrotomy may be necessary to locate and remove foreign bodies that have entered the knee joint, which can cause pain, inflammation, and further complications.
  • Joint Exploration: The procedure is performed to explore the knee joint when there are unexplained symptoms or conditions that require direct visualization and assessment of the joint structures.

2. Procedure

The procedure for CPT® Code 27310 involves several critical steps to ensure effective exploration and treatment of the knee joint. The following outlines the procedural steps:

  • Step 1: A skin incision is made over the knee joint, allowing access to the underlying tissues. This incision is carefully planned to minimize damage to surrounding structures.
  • Step 2: The surgeon dissects through the tissues to expose the joint capsule. This step is crucial for gaining access to the knee joint itself.
  • Step 3: Once the joint capsule is exposed, it is opened to allow for exploration of the knee joint. This step enables the surgeon to assess the internal condition of the joint.
  • Step 4: If an infection is present, the surgeon drains any fluid that may include blood and purulent matter from the knee joint. This is essential for alleviating pressure and reducing the risk of further complications.
  • Step 5: Cultures are obtained from the drained fluid and sent for laboratory analysis. This step is important for identifying the specific pathogens involved in the infection.
  • Step 6: The knee joint is flushed with saline solution to remove any debris and contaminants, ensuring a clean environment for healing.
  • Step 7: Any foreign bodies located within the joint are carefully removed. This is a critical step to prevent ongoing irritation and inflammation.
  • Step 8: The knee is flushed again with saline solution to ensure that all debris and contaminants have been cleared from the joint.
  • Step 9: Drains may be placed as needed to facilitate post-operative fluid drainage, which helps prevent fluid accumulation and promotes healing.
  • Step 10: Finally, the incision is closed in layers around the drain, and a dressing is applied to protect the surgical site during the recovery process.

3. Post-Procedure

After the arthrotomy procedure, patients can expect specific post-operative care and considerations. The placement of drains, if utilized, will help manage any excess fluid accumulation and reduce the risk of infection. Patients are typically monitored for signs of infection, such as increased redness, swelling, or discharge from the incision site. Pain management is also an important aspect of post-procedure care, and patients may be prescribed analgesics to manage discomfort. Rehabilitation and physical therapy may be recommended to restore function and mobility in the knee joint, depending on the extent of the procedure and the patient's overall condition. Follow-up appointments will be necessary to assess healing, remove drains if present, and evaluate the need for further interventions based on the initial findings and laboratory results.

Short Descr EXPLORATION OF KNEE JOINT
Medium Descr ARTHRT KNE W/EXPL DRG/RMVL FB
Long Descr Arthrotomy, knee, with exploration, drainage, or removal of foreign body (eg, infection)
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 Hospital Part B services paid through a comprehensive APC
ASC Payment Indicator Surgical procedure on ASC list in CY 2007; payment based on OPPS relative payment weight.
Type of Service (TOS) 2 - Surgery
Berenson-Eggers TOS (BETOS) P5B - Ambulatory procedures - musculoskeletal
MUE 1
CCS Clinical Classification 162 - Other OR therapeutic procedures on joints

This is a primary code that can be used with these additional add-on codes.

20700 Add-on Code MPFS Status: Active Code APC N ASC N1 Manual preparation and insertion of drug-delivery device(s), deep (eg, subfascial) (List separately in addition to code for primary procedure)
20704 Add-on Code MPFS Status: Active Code APC N Manual preparation and insertion of drug-delivery device(s), intra-articular (List separately in addition to code for primary procedure)
20705 Add-on Code MPFS Status: Active Code APC N Removal of drug-delivery device(s), intra-articular (List separately in addition to code for primary procedure)
RT Right side (used to identify procedures performed on the right side of the body)
LT Left side (used to identify procedures performed on the left side of the body)
AS Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery
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.)
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.
GC This service has been performed in part by a resident under the direction of a teaching physician
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.
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).
XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service
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).
54 Surgical care only: when 1 physician or other qualified health care professional performs a surgical procedure and another provides preoperative and/or postoperative management, surgical services may be identified by adding modifier 54 to the usual procedure number.
55 Postoperative management only: when 1 physician or other qualified health care professional performed the postoperative management and another performed the surgical procedure, the postoperative component may be identified by adding modifier 55 to the usual procedure number.
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.
74 Discontinued out-patient hospital/ambulatory surgery center (asc) procedure after administration of anesthesia: due to extenuating circumstances or those that threaten the well being of the patient, the physician may terminate a surgical or diagnostic procedure after the administration of anesthesia (local, regional block(s), general) or after the procedure was started (incision made, intubation started, scope inserted, etc). under these circumstances, the procedure started but terminated can be reported by its usual procedure number and the addition of modifier 74. note: the elective cancellation of a service prior to the administration of anesthesia and/or surgical preparation of the patient should not be reported. for physician reporting of a discontinued procedure, see modifier 53.
76 Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
77 Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
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).
AF Specialty physician
AG Primary physician
AQ Physician providing a service in an unlisted health professional shortage area (hpsa)
CC Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed)
ET Emergency services
GV Attending physician not employed or paid under arrangement by the patient's hospice provider
GW Service not related to the hospice patient's terminal condition
GZ Item or service expected to be denied as not reasonable and necessary
PD Diagnostic or related non diagnostic item or service provided in a wholly owned or operated entity to a patient who is admitted as an inpatient within 3 days
Q1 Routine clinical service provided in a clinical research study that is in an approved clinical research study
Q6 Service furnished under a fee-for-time compensation arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area
SG Ambulatory surgical center (asc) facility service
X4 Episodic/focused services: for reporting services by clinicians who provide focused care on particular types of treatment limited to a defined period and circumstance; the patient has a problem, acute or chronic, that will be treated with surgery, radiation, or some other type of generally time-limited intervention; reporting clinician service examples include but are not limited to, the orthopedic surgeon performing a knee replacement and seeing the patient through the postoperative period
XE Separate encounter, a service that is distinct because it occurred during a separate encounter
XS Separate structure, a service that is distinct because it was performed on a separate organ/structure
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