Medial Femoral Trochlea Osteochondral Free Flap Reconstruction versus Proximal Row Carpectomy for Advanced Kienbock's Disease: A Three Dimensional Morphometric Comparison
Amelia C. Van Handel, M.D.1; Leigha M. Lynch, Ph.D.2; Jimmy H. Daruwalla, M.D.3; James P. Higgins, M.D.4; Kari L. Allen, Ph.D.5; Mitchell A Pet, M.D.6
1Washington University in St. Louis, St. Louis, MO; 2Washington University in St. Louis, St Louis, MO; 3Curtis National Hand Center MedStar Union Memorial Hospital, Baltimore, MD; 4Curtis National Hand Center, MedStar Union Memorial Hospital, Batimore, MD; 5Washington University School of Medicine, St. Louis, MO; 6Washington University School of Medicine, Saint Louis, MO
Introduction
In cases of advanced Kienbock’s Disease (KD) with fragmentation of the proximal lunate (PL) articular surface, surgical options include proximal row carpectomy (PRC) or lunate reconstruction with a medial femoral trochlea (MFT) osteochondral free flap. One theoretical advantage of MFT over PRC is that the shape of the PL may be more closely approximated by the MFT than by the proximal capitate (PC). However, this has not been proven. This study aims to evaluate the PC and MFT flap to determine which more faithfully recreates the shape of the PL.
Materials & Methods
MRIs of the ipsilateral knee and wrist were obtained from 5 healthy volunteers aged 18-35 years. The PL and PC articular surfaces were extracted from each wrist. The MFT osteochondral flap was extracted from each knee MRI using a post-operative knee MRI from a patient who had previously undergone MFT flap harvest as a negative virtual template. For each subject, the 3D surfaces of the MFT and PC were each superimposed onto the matched PL for quantitative and qualitative 3-dimensional morphometric comparison. Distances between corresponding points on the PL and PC or MFT surfaces were calculated for each patient. Two-tailed student t-tests (p>0.05) were used to evaluate the difference between the PL-PC and PL-MFT distances in each subject. Heat maps of localized distances were projected onto the PL of each subject to visualize the regional homology between the two reconstructions.
Results
The mean for the PL-MFT pair was significantly lower (i.e. less distance between surfaces) than for the PL-PC pair in 3/5 subjects. One subject showed no significant difference between the PL-PC and PL-MFT reconstructions (p=0.159), and one showed a significantly higher mean for the PL-MFT than the PL-PC (p=0.042). Heat maps of surface similarity demonstrate that the PL-PC tends to have a smaller area of homology (in blue) than the PL-MFT reconstruction, reflecting the marked curvature of the capitate’s articular surface around the periphery (Figure 1).
Conclusions
As compared to the PC, the MFT flap more faithfully recreates the shape of the PL in the majority of patients, but there are cases in which the PRC may equivalent or superior. The inter-patient variability suggests as presurgical planning becomes more available and practical, virtual surface evaluation be of value in determining the best operation in each patient.
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