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A Contemporary Classification System of Femoral Bone Loss in Revision Total Hip Arthroplasty
Bryeson Rodgers1, Gabrielle Wernick1, Gabrielle Roman1
1Department of Orthopaedic Surgery, Mayo Clinic Arizona, Phoenix, Arizona, USA.
Insights
Existing femoral bone loss classifications are outdated. A novel classification system (NCS) better predicts reoperation risk in revision total hip arthroplasty, guiding modern implant selection for improved patient outcomes.
Area of Science:
- Orthopedic Surgery
- Biomaterials Science
- Medical Imaging Analysis
Background:
- Current classification systems for femoral bone loss in revision total hip arthroplasty (rTHA) predate modern implant designs.
- Predominant use of fluted-tapered titanium stems necessitates updated classification methods.
- Existing systems may limit guidance for contemporary reconstructive techniques.
Purpose of the Study:
- To introduce a novel classification system (NCS) for femoral bone loss.
- To evaluate the NCS's ability to guide implant selection in rTHA.
- To compare the predictive value of the NCS against the Paprosky classification for reoperation risk.
Main Methods:
- Retrospective review of 442 femoral revisions (2007-2019).
- Assessment of femoral bone loss using Paprosky classification and the novel NCS.
- Comparison of reoperation rates based on classification systems.
Main Results:
- The novel classification system (NCS) demonstrated a higher predictive value for reoperation compared to the Paprosky classification (P = .008).
- NCS identified 5 types of femoral bone loss, with Type 2 being most prevalent (82.4%).
- Reoperation rates included infection (5.1%), instability (2.8%), and femoral loosening (1.4%).
Conclusions:
- A novel femoral classification system (NCS) is presented for rTHA.
- The NCS aids in guiding contemporary implant selection.
- The NCS is more predictive of reoperation than the Paprosky classification.
Background:
Current femoral bone loss classification systems in revision total hip arthroplasty were created at a time when the predominant reconstructive methods used cylindrical porous-coated cobalt-chrome stems. As these stems have largely been replaced by fluted-tapered titanium stems, the ability of these classification systems to help guide implant selection is limited. The purpose of this study was to describe a novel classification system based on contemporary reconstructive techniques.
Methods:
We reviewed the charts of all patients who underwent femoral component revision at our institution from 2007 through 2019. Preoperative images were reviewed, and FBL was rated according to the Paprosky classification and compared to ratings using our institution's NCS. Rates of reoperation at the time of most recent follow-up were determined and compared.
Results:
Four-hundred and forty-two femoral revisions in 330 patients with a mean follow-up duration of 2.7 years were identified. Femoral type according to Paprosky and NCS were Paprosky I (36, 8.1%), II (61, 13.8%), IIIA (180, 40.7%), IIIB (116, 26.2%), and IV (49 11.1%) and NCS 1 (35, 7.9%), 2 (364, 82.4%), 3 (8, 1.8%), 4 (27, 6.1%), and 5 (8, 1.8%). Of the 353 nonstaged rTHAs, there were 42 cases requiring unplanned reoperation (11.9%), including infection (18, 5.1%), instability (10, 2.8%), femoral loosening (5, 1.4%), and various other causes (9, 2.5%). The NCS was more predictive of reoperation than the Paprosky classification (Fisher's exact test, P = .008 vs P = ns, respectively).
Conclusion:
We present a novel femoral classification system that can help guide contemporary implant selection.
