It's all about compartments when it comes to coding arthroscopic knee procedures. You must bundle procedures performed in the same compartment — meaning that you may report only the single highest-level procedure — but you can report multiple CPT codes when your surgeons do work in separate compartments. Making this distinction is the key to picking up all of the codes possible when coding knee procedures (see "5 Knee Arthroscopy Coding & Billing Tips" on page 21). Your surgeons can greatly assist you in maximizing reimbursement by dictating with compartments in mind. For example, your surgeons can dictate a separate paragraph for each compartment, stating what they saw and what they did in the medial compartment, the lateral compartment and so on.

Anatomy lesson
To understand compartments, we first must understand some knee anatomy:

• Medial compartment. The area between the femur and tibia on the "inside" of the knee.
• Lateral compartment. The area between the femur and tibia on the "outside" of the knee.
• Patellofemoral compartment. The area between the undersurface of the patella and the femur.
• Intra-articular notch. Contains the ACL and PCL, but is not considered a separate compartment for coding purposes.

A review of CPT codes
Arthroscopic knee procedure CPT codes range from 29866 to 29889. CPT codes are grouped into 6 sections:

1. Mosaicplasty. Resurfacing technique consisting of transplantation of multiple osteochondral grafts to smooth the area.

• 29866 is for autografts (from the patient).
• 29867 is for allografts (tissue from the same species, but different genetic background).

2. Meniscal transplantation, medial or lateral (29868). Removal of the damaged portion of meniscus, creation of tibial tunnels or bone trough, and insertion and securing of meniscal graft.

3. Diagnostic arthroscopy (29870) — with or without biopsy. Note that this is always bundled if combined with a surgical procedure.

4. Surgical arthroscopy lavage & drainage (29871). Irrigation/ washing out.

5. Surgical arthroscopy (major section 29873 to 29887).

• 29873. With lateral release. To relieve chondromalacia patella, or "runner's knee."
• 29874. Removal of loose/foreign body using a grasper or shaver.
• 29875. Limited synovectomy. Removal of plica or shelf using a shaver.
• 29876. Major synovectomy. Removal in 2 or more compartments.
• 29877. Chondroplasty. Debridement/shaving of articular cartilage.
• 29879. Abrasion arthroplasty, may include chondroplasty. A bur is used to remove dead bone in order to activate blood vessels and induce scab formation and subsequent healing of the articular cartilage.
• 29880. Medial and lateral meniscectomy (partial or total resection of the meniscus), including meniscal shaving.
• 29881. Medial or lateral meniscectomy, including meniscal shaving.
• 29882. Medial or lateral meniscus repair (an additional incision is made on the side of the knee to pass sutures through the meniscal cartilage tear and then knotted to secure).
• 29883. Medial and lateral meniscus repair.
• 29884. Lysis of adhesions. Cutting and removal of scar tissue and possible subsequent manipulation.
• 29885. Osteochondritis dessicans. Drilling, with bone grafting, with or without internal fixation.
• 29886. Osteochondritis dessicans. Drilling for intact lesion. Drilling only, no bone grafting or fixation.
• 29887. Osteochondritis dessicans. Drilling for intact lesion, with internal fixation, no bone grafting.

6. ACL (29888) or PCL (29889)