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MS-DRG 522 · MDC 08 · Surgical

MS-DRG 522: Hip Replacement with Principal Diagnosis of Hip Fracture without MCC

Reviewed by QuickIntell RCM Editorial Team · Last reviewed

Data effective
Data currency: IPPS Table 5 FY2027 final rule (effective October 1, 2026); Definitions Manual v44 (effective October 1, 2026). Next CMS release: April 1, 2027 (v44.1 mid-year update), then the FY2028 final rule in August 2027.

Key facts for DRG 522

FY2027 relative weight
2.1160
Higher than 65% of all MS-DRGs
Change vs FY2026
-0.1%
FY2026 weight 2.1180
Geometric mean LOS
4.0 days
Arithmetic mean 4.4 days
MDC
08
Diseases and Disorders of the Musculoskeletal System and Connective Tissue
Severity level
without MCC
Transfer policy
Post-acute transfer DRG
Special-pay DRG

TL;DR

MS-DRG 522 is a surgical group in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue) at the base severity level of its family. CMS assigns it a FY2027 relative weight of 2.1160 with a geometric mean length of stay of 4.0 days and an arithmetic mean of 4.4. Its weight moved down 0.1% from FY2026 (2.1180). That weight is higher than 65% of all surgical and medical MS-DRGs. Its CC/MCC family (DRG 521) spans weights 2.1160 to 2.8520. The v44 Definitions Manual assigns it through 1232 principal diagnosis codes and 96 and operating room procdures codes.

What changed from FY2026 to FY2027

CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 522 the FY2027 relative weight is 2.1160 against 2.1180 in FY2026, a fall of 0.09%.

FY2026 versus FY2027 payment factors for MS-DRG 522
MetricFY2026FY2027Change
Relative weight2.11802.1160-0.0020
Geometric mean LOS (days)4.04.0+0.0
Arithmetic mean LOS (days)4.54.4-0.1
Weights shown are the FY2027 final values after the 10% cap on year-over-year reductions where applicable.

CC and MCC family

DRG 522 shares its base definition with 1 other MS-DRG split by severity. The family's weights span 2.1160 to 2.8520, a 1.35× spread, which is the payment effect of documenting qualifying complications and comorbidities.

MS-DRGs in the same base group as DRG 522
DRGTitleFY2027 weightGMLOS
521Hip Replacement with Principal Diagnosis of Hip Fracture with MCC2.85205.9
522Hip Replacement with Principal Diagnosis of Hip Fracture without MCC2.11604.0

Grouper logic (v44 Definitions Manual)

Principal Diagnosis: 1232 ICD-10 codes drive assignment to this group; the first 12 are shown.

Principal Diagnosis codes assigned to DRG 522 (sample)
ICD-10 codeDescription
M80051AAge-related osteoporosis with current pathological fracture, right femur, initial encounter for fracture
M80051GAge-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with delayed healing
M80051KAge-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with nonunion
M80051PAge-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with malunion
M80052AAge-related osteoporosis with current pathological fracture, left femur, initial encounter for fracture
M80052GAge-related osteoporosis with current pathological fracture, left femur, subsequent encounter for fracture with delayed healing
M80052KAge-related osteoporosis with current pathological fracture, left femur, subsequent encounter for fracture with nonunion
M80052PAge-related osteoporosis with current pathological fracture, left femur, subsequent encounter for fracture with malunion
M80059AAge-related osteoporosis with current pathological fracture, unspecified femur, initial encounter for fracture
M80059GAge-related osteoporosis with current pathological fracture, unspecified femur, subsequent encounter for fracture with delayed healing
M80059KAge-related osteoporosis with current pathological fracture, unspecified femur, subsequent encounter for fracture with nonunion
M80059PAge-related osteoporosis with current pathological fracture, unspecified femur, subsequent encounter for fracture with malunion

And Operating Room Procdures: 96 ICD-10 codes drive assignment to this group; the first 12 are shown.

And Operating Room Procdures codes assigned to DRG 522 (sample)
ICD-10 codeDescription
0SR9019Replacement of Right Hip Joint with Metal Synthetic Substitute, Cemented, Open Approach
0SR901AReplacement of Right Hip Joint with Metal Synthetic Substitute, Uncemented, Open Approach
0SR901ZReplacement of Right Hip Joint with Metal Synthetic Substitute, Open Approach
0SR9029Replacement of Right Hip Joint with Metal on Polyethylene Synthetic Substitute, Cemented, Open Approach
0SR902AReplacement of Right Hip Joint with Metal on Polyethylene Synthetic Substitute, Uncemented, Open Approach
0SR902ZReplacement of Right Hip Joint with Metal on Polyethylene Synthetic Substitute, Open Approach
0SR9039Replacement of Right Hip Joint with Ceramic Synthetic Substitute, Cemented, Open Approach
0SR903AReplacement of Right Hip Joint with Ceramic Synthetic Substitute, Uncemented, Open Approach
0SR903ZReplacement of Right Hip Joint with Ceramic Synthetic Substitute, Open Approach
0SR9049Replacement of Right Hip Joint with Ceramic on Polyethylene Synthetic Substitute, Cemented, Open Approach
0SR904AReplacement of Right Hip Joint with Ceramic on Polyethylene Synthetic Substitute, Uncemented, Open Approach
0SR904ZReplacement of Right Hip Joint with Ceramic on Polyethylene Synthetic Substitute, Open Approach

Documentation and denial exposure

As a surgical DRG, assignment depends on a qualifying operating-room procedure being coded from the operative report; a missing or non-OR procedure code drops the stay into a medical DRG in MDC 08 with a lower weight. Because this family splits by severity, auditors target CC and MCC capture: each secondary diagnosis must be documented as present, monitored, evaluated or treated during the stay to survive a DRG-validation review. Typical inpatient denial codes for this group: CARC 16 (claim lacks information needed to group the stay), CARC 50 (the admission or procedure is judged not medically necessary), CARC 97 (a service is bundled into the DRG payment).

How QuickIntell uses DRG 522 data

QuickCode groups inpatient encounters against the current v44 logic, flags CC and MCC candidates that lack supporting documentation, and shows the weight difference across the family before the claim drops. QuickScribe captures the attending's language that supports severity, and QuickRCM works DRG-validation denials with the grouper evidence attached.

Explore QuickCodeExplore QuickScribeBook a demo

Frequently asked questions — DRG 522

What is MS-DRG 522?

MS-DRG 522 is "Hip Replacement with Principal Diagnosis of Hip Fracture without MCC", a surgical Medicare Severity Diagnosis-Related Group in MDC 08, Diseases and Disorders of the Musculoskeletal System and Connective Tissue. Medicare pays inpatient stays grouped here at the hospital's base rate multiplied by the DRG relative weight.

What is the FY2027 relative weight for DRG 522?

The FY2027 relative weight is 2.1160 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 2.1180, a change of -0.1%.

What is the average length of stay for DRG 522?

CMS reports a geometric mean length of stay of 4.0 days and an arithmetic mean of 4.4 days for FY2027. The geometric mean is used for transfer-payment calculations.

Which DRGs are in the same CC/MCC family as 522?

DRG 521 (Hip Replacement with Principal Diagnosis of Hip Fracture with MCC, weight 2.8520). The family's weights range from 2.1160 to 2.8520, so documented complications and comorbidities change payment materially.

What documentation supports the severity level of DRG 522?

DRG 522 is the base-severity assignment: no secondary diagnosis on the CC or MCC lists was coded, or the only ones present are excluded for this principal diagnosis. Revenue-integrity review here looks for undercapture, meaning conditions treated during the stay (electrolyte disorders, specified anemia, acute blood loss, pressure injuries present on admission) that were never documented to the specificity the lists require. A compliant query to the attending, not a coder assumption, is the only way to move a stay to the CC or MCC sibling.

Which codes group to DRG 522?

The v44 Definitions Manual lists 1232 principal diagnosis codes and 96 and operating room procdures codes for this group. Examples from the principal diagnosis list: M80051A (Age-related osteoporosis with current pathological fracture, right femur, initial encounter for fracture); M80051G (Age-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with delayed healing); M80051K (Age-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with nonunion); M80051P (Age-related osteoporosis with current pathological fracture, right femur, subsequent encounter for fracture with malunion).

Is DRG 522 a post-acute transfer DRG?

Yes. CMS flags DRG 522 under the post-acute care transfer policy, so a discharge to a qualifying post-acute setting before the geometric mean length of stay is paid a per-diem amount rather than the full DRG payment. It is also a special-pay DRG.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-01. Verify against the primary file before billing or contracting decisions.

Disclaimer

This page is an operational reference compiled from the CMS IPPS FY2027 final rule (Table 5) and the v44 ICD-10 MS-DRG Definitions Manual. Relative weights are national factors; actual payment depends on each hospital's wage-adjusted base rate, add-ons, outliers and transfer adjustments. Nothing here is legal, clinical or billing advice; verify grouping against your encoder and the published CMS files.