MS-DRG · FY 2026 v43.0

MS-DRG 550 – Septic Arthritis without CC/MCC

A Medical DRG in MDC 08 (Diseases & Disorders of the Musculoskeletal System & Connective Tissue). Inpatient cases group to DRG 550 when the ICD-10-CM principal diagnosis is one of the 155 codes listed below and no secondary diagnosis on the CC or MCC lists is present. Its FY 2026 relative weight is 0.8741 with a geometric mean length of stay of 3.1 days.

Medical DRG – assigned by principal diagnosis✓ Official CMS v43.0 dataset
0.8741
Relative Weight
3.1
Geometric Mean LOS (days)
3.7
Arithmetic Mean LOS (days)
155
Principal Diagnosis Codes

Severity family

DRG 548with MCCWeight 1.9309 · GMLOS 5.9 daysDRG 549with CCWeight 1.2072 · GMLOS 3.9 daysDRG 550without CC/MCCWeight 0.8741 · GMLOS 3.1 days
How a case is assigned to DRG 550

The grouper first assigns the case to MDC 08 from the principal diagnosis and finds no qualifying operating-room procedure (this is a Medical DRG; ICD-10-PCS codes do not drive assignment here), then applies the severity split from secondary diagnoses: with MCC → 548; with CC → 549; without CC/MCC → 550.

ICD-10-CM

Principal Diagnosis Codes 155 codes · 8 categories

155 of 155 shown
A02 Other salmonella infections1 code
A18 Tuberculosis of other organs2 codes
  • A18.02 Tuberculous arthritis of other joints
  • A18.09 Other musculoskeletal tuberculosis
A39 Meningococcal infection2 codes
  • A39.83 Meningococcal arthritis
  • A39.84 Postmeningococcal arthritis
A54 Gonococcal infection4 codes
  • A54.40 Gonococcal infection of musculoskeletal system, unspecified
  • A54.42 Gonococcal arthritis
  • A54.43 Gonococcal osteomyelitis
  • A54.49 Gonococcal infection of other musculoskeletal tissue
A66 Yaws1 code
  • A66.6 Bone and joint lesions of yaws
M00 Pyogenic arthritis97 codes
  • M00.00 Staphylococcal arthritis, unspecified joint
  • M00.011 Staphylococcal arthritis, right shoulder
  • M00.012 Staphylococcal arthritis, left shoulder
  • M00.019 Staphylococcal arthritis, unspecified shoulder
  • M00.021 Staphylococcal arthritis, right elbow
  • M00.022 Staphylococcal arthritis, left elbow
  • M00.029 Staphylococcal arthritis, unspecified elbow
  • M00.031 Staphylococcal arthritis, right wrist
  • M00.032 Staphylococcal arthritis, left wrist
  • M00.039 Staphylococcal arthritis, unspecified wrist
  • M00.041 Staphylococcal arthritis, right hand
  • M00.042 Staphylococcal arthritis, left hand
  • M00.049 Staphylococcal arthritis, unspecified hand
  • M00.051 Staphylococcal arthritis, right hip
  • M00.052 Staphylococcal arthritis, left hip
  • M00.059 Staphylococcal arthritis, unspecified hip
  • M00.061 Staphylococcal arthritis, right knee
  • M00.062 Staphylococcal arthritis, left knee
  • M00.069 Staphylococcal arthritis, unspecified knee
  • M00.071 Staphylococcal arthritis, right ankle and foot
  • M00.072 Staphylococcal arthritis, left ankle and foot
  • M00.079 Staphylococcal arthritis, unspecified ankle and foot
  • M00.08 Staphylococcal arthritis, vertebrae
  • M00.09 Staphylococcal polyarthritis
  • M00.10 Pneumococcal arthritis, unspecified joint
  • M00.111 Pneumococcal arthritis, right shoulder
  • M00.112 Pneumococcal arthritis, left shoulder
  • M00.119 Pneumococcal arthritis, unspecified shoulder
  • M00.121 Pneumococcal arthritis, right elbow
  • M00.122 Pneumococcal arthritis, left elbow
  • M00.129 Pneumococcal arthritis, unspecified elbow
  • M00.131 Pneumococcal arthritis, right wrist
  • M00.132 Pneumococcal arthritis, left wrist
  • M00.139 Pneumococcal arthritis, unspecified wrist
  • M00.141 Pneumococcal arthritis, right hand
  • M00.142 Pneumococcal arthritis, left hand
  • M00.149 Pneumococcal arthritis, unspecified hand
  • M00.151 Pneumococcal arthritis, right hip
  • M00.152 Pneumococcal arthritis, left hip
  • M00.159 Pneumococcal arthritis, unspecified hip
  • M00.161 Pneumococcal arthritis, right knee
  • M00.162 Pneumococcal arthritis, left knee
  • M00.169 Pneumococcal arthritis, unspecified knee
  • M00.171 Pneumococcal arthritis, right ankle and foot
  • M00.172 Pneumococcal arthritis, left ankle and foot
  • M00.179 Pneumococcal arthritis, unspecified ankle and foot
  • M00.18 Pneumococcal arthritis, vertebrae
  • M00.19 Pneumococcal polyarthritis
  • M00.20 Other streptococcal arthritis, unspecified joint
  • M00.211 Other streptococcal arthritis, right shoulder
  • M00.212 Other streptococcal arthritis, left shoulder
  • M00.219 Other streptococcal arthritis, unspecified shoulder
  • M00.221 Other streptococcal arthritis, right elbow
  • M00.222 Other streptococcal arthritis, left elbow
  • M00.229 Other streptococcal arthritis, unspecified elbow
  • M00.231 Other streptococcal arthritis, right wrist
  • M00.232 Other streptococcal arthritis, left wrist
  • M00.239 Other streptococcal arthritis, unspecified wrist
  • M00.241 Other streptococcal arthritis, right hand
  • M00.242 Other streptococcal arthritis, left hand
  • M00.249 Other streptococcal arthritis, unspecified hand
  • M00.251 Other streptococcal arthritis, right hip
  • M00.252 Other streptococcal arthritis, left hip
  • M00.259 Other streptococcal arthritis, unspecified hip
  • M00.261 Other streptococcal arthritis, right knee
  • M00.262 Other streptococcal arthritis, left knee
  • M00.269 Other streptococcal arthritis, unspecified knee
  • M00.271 Other streptococcal arthritis, right ankle and foot
  • M00.272 Other streptococcal arthritis, left ankle and foot
  • M00.279 Other streptococcal arthritis, unspecified ankle and foot
  • M00.28 Other streptococcal arthritis, vertebrae
  • M00.29 Other streptococcal polyarthritis
  • M00.80 Arthritis due to other bacteria, unspecified joint
  • M00.811 Arthritis due to other bacteria, right shoulder
  • M00.812 Arthritis due to other bacteria, left shoulder
  • M00.819 Arthritis due to other bacteria, unspecified shoulder
  • M00.821 Arthritis due to other bacteria, right elbow
  • M00.822 Arthritis due to other bacteria, left elbow
  • M00.829 Arthritis due to other bacteria, unspecified elbow
  • M00.831 Arthritis due to other bacteria, right wrist
  • M00.832 Arthritis due to other bacteria, left wrist
  • M00.839 Arthritis due to other bacteria, unspecified wrist
  • M00.841 Arthritis due to other bacteria, right hand
  • M00.842 Arthritis due to other bacteria, left hand
  • M00.849 Arthritis due to other bacteria, unspecified hand
  • M00.851 Arthritis due to other bacteria, right hip
  • M00.852 Arthritis due to other bacteria, left hip
  • M00.859 Arthritis due to other bacteria, unspecified hip
  • M00.861 Arthritis due to other bacteria, right knee
  • M00.862 Arthritis due to other bacteria, left knee
  • M00.869 Arthritis due to other bacteria, unspecified knee
  • M00.871 Arthritis due to other bacteria, right ankle and foot
  • M00.872 Arthritis due to other bacteria, left ankle and foot
  • M00.879 Arthritis due to other bacteria, unspecified ankle and foot
  • M00.88 Arthritis due to other bacteria, vertebrae
  • M00.89 Polyarthritis due to other bacteria
  • M00.9 Pyogenic arthritis, unspecified
M01 Direct infections of joint in infectious and parasitic diseases classified elsewhere24 codes
  • M01.X0 Direct infection of unspecified joint in infectious and parasitic diseases classified elsewhere
  • M01.X11 Direct infection of right shoulder in infectious and parasitic diseases classified elsewhere
  • M01.X12 Direct infection of left shoulder in infectious and parasitic diseases classified elsewhere
  • M01.X19 Direct infection of unspecified shoulder in infectious and parasitic diseases classified elsewhere
  • M01.X21 Direct infection of right elbow in infectious and parasitic diseases classified elsewhere
  • M01.X22 Direct infection of left elbow in infectious and parasitic diseases classified elsewhere
  • M01.X29 Direct infection of unspecified elbow in infectious and parasitic diseases classified elsewhere
  • M01.X31 Direct infection of right wrist in infectious and parasitic diseases classified elsewhere
  • M01.X32 Direct infection of left wrist in infectious and parasitic diseases classified elsewhere
  • M01.X39 Direct infection of unspecified wrist in infectious and parasitic diseases classified elsewhere
  • M01.X41 Direct infection of right hand in infectious and parasitic diseases classified elsewhere
  • M01.X42 Direct infection of left hand in infectious and parasitic diseases classified elsewhere
  • M01.X49 Direct infection of unspecified hand in infectious and parasitic diseases classified elsewhere
  • M01.X51 Direct infection of right hip in infectious and parasitic diseases classified elsewhere
  • M01.X52 Direct infection of left hip in infectious and parasitic diseases classified elsewhere
  • M01.X59 Direct infection of unspecified hip in infectious and parasitic diseases classified elsewhere
  • M01.X61 Direct infection of right knee in infectious and parasitic diseases classified elsewhere
  • M01.X62 Direct infection of left knee in infectious and parasitic diseases classified elsewhere
  • M01.X69 Direct infection of unspecified knee in infectious and parasitic diseases classified elsewhere
  • M01.X71 Direct infection of right ankle and foot in infectious and parasitic diseases classified elsewhere
  • M01.X72 Direct infection of left ankle and foot in infectious and parasitic diseases classified elsewhere
  • M01.X79 Direct infection of unspecified ankle and foot in infectious and parasitic diseases classified elsewhere
  • M01.X8 Direct infection of vertebrae in infectious and parasitic diseases classified elsewhere
  • M01.X9 Direct infection of multiple joints in infectious and parasitic diseases classified elsewhere
M02 Postinfective and reactive arthropathies24 codes
  • M02.80 Other reactive arthropathies, unspecified site
  • M02.811 Other reactive arthropathies, right shoulder
  • M02.812 Other reactive arthropathies, left shoulder
  • M02.819 Other reactive arthropathies, unspecified shoulder
  • M02.821 Other reactive arthropathies, right elbow
  • M02.822 Other reactive arthropathies, left elbow
  • M02.829 Other reactive arthropathies, unspecified elbow
  • M02.831 Other reactive arthropathies, right wrist
  • M02.832 Other reactive arthropathies, left wrist
  • M02.839 Other reactive arthropathies, unspecified wrist
  • M02.841 Other reactive arthropathies, right hand
  • M02.842 Other reactive arthropathies, left hand
  • M02.849 Other reactive arthropathies, unspecified hand
  • M02.851 Other reactive arthropathies, right hip
  • M02.852 Other reactive arthropathies, left hip
  • M02.859 Other reactive arthropathies, unspecified hip
  • M02.861 Other reactive arthropathies, right knee
  • M02.862 Other reactive arthropathies, left knee
  • M02.869 Other reactive arthropathies, unspecified knee
  • M02.871 Other reactive arthropathies, right ankle and foot
  • M02.872 Other reactive arthropathies, left ankle and foot
  • M02.879 Other reactive arthropathies, unspecified ankle and foot
  • M02.88 Other reactive arthropathies, vertebrae
  • M02.89 Other reactive arthropathies, multiple sites
ICD-10-PCS

Procedure Codes

Procedure codes do not drive assignment for this DRG. DRG 550 is a Medical DRG, assigned from the principal diagnosis above.

Frequently Asked Questions

What is MS-DRG 550?

MS-DRG 550 (Septic Arthritis without CC/MCC) is a medical DRG in MDC 08 (Diseases & Disorders of the Musculoskeletal System & Connective Tissue). Its FY 2026 relative weight is 0.8741 with a geometric mean length of stay of 3.1 days.

What is the difference between DRG 548, 549, 550?

All 3 share the same base category; the severity of secondary diagnoses separates them: 548 (with MCC), 549 (with CC), 550 (without CC/MCC). A major complication or comorbidity (MCC) places the case in the highest-weighted DRG of the family; a CC in the middle; neither in the lowest.

How many diagnosis codes group to DRG 550?

155 ICD-10-CM principal diagnosis codes group to this DRG, spanning 8 three-character categories.

What is the relative weight of DRG 550?

The FY 2026 relative weight of this DRG is 0.8741, meaning reimbursement of roughly 0.87 times the average Medicare inpatient case. Multiply by a hospital's blended base rate for the approximate payment.

← PreviousDRG 549 – Septic Arthritis with CC
Source: CMS ICD-10 MS-DRG v43.0 Definitions Manual and the FY 2026 IPPS Final Rule (Table 5), effective October 1, 2025 through September 30, 2026. We publish the DRG assignments as CMS defines them and add the navigation, search, and code links.