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Three-dimensional postoperative accuracy of extra-articular forearm osteotomies using CT-scan based patient-specific surgical guides.

Vlachopoulos L, Schweizer A, Graf M, Nagy L, Fürnstahl P - BMC Musculoskelet Disord (2015)

Bottom Line: However, the difference between planned and performed reduction is difficult to assess with conventional radiographs.The technique demonstrated high accuracy in performing closing wedge (or single-cut) osteotomies.However, for opening wedge osteotomies with extensive lengthening, probably due to the fact that precise reduction was difficult to achieve or maintain, the final corrections were less accurate.

View Article: PubMed Central - PubMed

Affiliation: Computer Assisted Research and Development Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. lvlachopoulos@card.balgrist.ch.

ABSTRACT

Background: Computer assisted corrective osteotomy of the diaphyseal forearm and the distal radius based on computer simulation and patient-specific guides has been described as a promising technique for accurate reconstruction of forearm deformities. Thereby, the intraoperative use of patient-specific drill and cutting guides facilitate the transfer of the preoperative plan to the surgery. However, the difference between planned and performed reduction is difficult to assess with conventional radiographs. The aim of this study was to evaluate the accuracy of this surgical technique based on postoperative three-dimensional (3D) computed tomography (CT) data.

Methods: Fourteen patients (mean age 23.2 (range, 12-58) years) with an extra-articular deformity of the forearm had undergone computer assisted corrective osteotomy with the healthy anatomy of the contralateral uninjured side as a reconstruction template. 3D bone surface models of the pathological and contralateral side were created from CT data for the computer simulation. Patient-specific drill and cutting guides including the preoperative planned screw direction of the angular-stable locking plates and the osteotomy planes were used for the intraoperative realization of the preoperative plan. There were seven opening wedge osteotomies and nine closing wedge (or single-cut) osteotomies performed. Eight-ten weeks postoperatively CT scans were obtained to assess bony consolidation and additionally used to generate a 3D model of the forearm. The simulated osteotomies- preoperative bone models with simulated correction - and the performed osteotomies - postoperative bone models - were analyzed for residual differences in 3D alignment.

Results: On average, a significant higher residual rotational deformity was observed in opening wedge osteotomies (8.30° ± 5.35°) compared to closing wedge osteotomies (3.47° ± 1.09°). The average residual translation was comparable small in both groups, i.e., below 1.5 mm and 1.1 mm for opening and closing wedge osteotomies, respectively.

Conclusions: The technique demonstrated high accuracy in performing closing wedge (or single-cut) osteotomies. However, for opening wedge osteotomies with extensive lengthening, probably due to the fact that precise reduction was difficult to achieve or maintain, the final corrections were less accurate.

No MeSH data available.


Related in: MedlinePlus

Postoperative Evaluation. The postoperative 3D evaluation is performed by comparing the preoperatively planned reduction (orange and violet fragments) with the bone model extracted from postoperative CT (cyan). a The proximal parts are superimposed. b The residual deformity is assessed by measuring the difference between the distal parts
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Fig2: Postoperative Evaluation. The postoperative 3D evaluation is performed by comparing the preoperatively planned reduction (orange and violet fragments) with the bone model extracted from postoperative CT (cyan). a The proximal parts are superimposed. b The residual deformity is assessed by measuring the difference between the distal parts

Mentions: During follow up plain radiographs were regularly acquired at 4 weeks, 8–10 weeks, 4 months and 12 months. Additionally, CT scans were performed 8–10 weeks postoperatively with the same scanning protocol as preoperatively to assess bony consolidation. Consolidation was defined as disappearance of the visibility of the osteotomy lines on plain radiographs, continuous bone trabeculae at least half of the diameter of the bone on CT and absence of pain or swelling at the level of the osteotomy. The CT data were used to generate a 3D model of the postoperative bone, the implant, and the screws by applying the same segmentation method as in the preoperative planning. The bone parts proximal to the osteotomy were used as a common reference for comparing the postoperative bone with the preoperatively planned reduction. The proximal parts were registered using ICP as shown in Fig. 2a. Thereafter, the difference between planned and performed reduction (i.e., residual deformity) was quantified in all six degrees of freedom by computing the difference between the distal bone parts using ICP (Fig. 2b). The resulting 4×4 transformation matrix was decomposed in a rotational and translation part: The residual rotation was expressed in axis-angle representation and additionally as three constitutive rotations (i.e., Euler rotations) [17] around a standardized coordinate system as depicted in Fig. 3. Rotation around the x-, y-, and z-axis of the coordinate systems correspond to rotations in the frontal (ulnar-/radialduction), transverse plane (pronation/supination), and sagittal (flexion/extension) plane, respectively. The residual translation was expressed as a 3D vector describing the displacement with respect to the same coordinate axes.Fig. 2


Three-dimensional postoperative accuracy of extra-articular forearm osteotomies using CT-scan based patient-specific surgical guides.

Vlachopoulos L, Schweizer A, Graf M, Nagy L, Fürnstahl P - BMC Musculoskelet Disord (2015)

Postoperative Evaluation. The postoperative 3D evaluation is performed by comparing the preoperatively planned reduction (orange and violet fragments) with the bone model extracted from postoperative CT (cyan). a The proximal parts are superimposed. b The residual deformity is assessed by measuring the difference between the distal parts
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4634814&req=5

Fig2: Postoperative Evaluation. The postoperative 3D evaluation is performed by comparing the preoperatively planned reduction (orange and violet fragments) with the bone model extracted from postoperative CT (cyan). a The proximal parts are superimposed. b The residual deformity is assessed by measuring the difference between the distal parts
Mentions: During follow up plain radiographs were regularly acquired at 4 weeks, 8–10 weeks, 4 months and 12 months. Additionally, CT scans were performed 8–10 weeks postoperatively with the same scanning protocol as preoperatively to assess bony consolidation. Consolidation was defined as disappearance of the visibility of the osteotomy lines on plain radiographs, continuous bone trabeculae at least half of the diameter of the bone on CT and absence of pain or swelling at the level of the osteotomy. The CT data were used to generate a 3D model of the postoperative bone, the implant, and the screws by applying the same segmentation method as in the preoperative planning. The bone parts proximal to the osteotomy were used as a common reference for comparing the postoperative bone with the preoperatively planned reduction. The proximal parts were registered using ICP as shown in Fig. 2a. Thereafter, the difference between planned and performed reduction (i.e., residual deformity) was quantified in all six degrees of freedom by computing the difference between the distal bone parts using ICP (Fig. 2b). The resulting 4×4 transformation matrix was decomposed in a rotational and translation part: The residual rotation was expressed in axis-angle representation and additionally as three constitutive rotations (i.e., Euler rotations) [17] around a standardized coordinate system as depicted in Fig. 3. Rotation around the x-, y-, and z-axis of the coordinate systems correspond to rotations in the frontal (ulnar-/radialduction), transverse plane (pronation/supination), and sagittal (flexion/extension) plane, respectively. The residual translation was expressed as a 3D vector describing the displacement with respect to the same coordinate axes.Fig. 2

Bottom Line: However, the difference between planned and performed reduction is difficult to assess with conventional radiographs.The technique demonstrated high accuracy in performing closing wedge (or single-cut) osteotomies.However, for opening wedge osteotomies with extensive lengthening, probably due to the fact that precise reduction was difficult to achieve or maintain, the final corrections were less accurate.

View Article: PubMed Central - PubMed

Affiliation: Computer Assisted Research and Development Group, Balgrist University Hospital, University of Zurich, Zurich, Switzerland. lvlachopoulos@card.balgrist.ch.

ABSTRACT

Background: Computer assisted corrective osteotomy of the diaphyseal forearm and the distal radius based on computer simulation and patient-specific guides has been described as a promising technique for accurate reconstruction of forearm deformities. Thereby, the intraoperative use of patient-specific drill and cutting guides facilitate the transfer of the preoperative plan to the surgery. However, the difference between planned and performed reduction is difficult to assess with conventional radiographs. The aim of this study was to evaluate the accuracy of this surgical technique based on postoperative three-dimensional (3D) computed tomography (CT) data.

Methods: Fourteen patients (mean age 23.2 (range, 12-58) years) with an extra-articular deformity of the forearm had undergone computer assisted corrective osteotomy with the healthy anatomy of the contralateral uninjured side as a reconstruction template. 3D bone surface models of the pathological and contralateral side were created from CT data for the computer simulation. Patient-specific drill and cutting guides including the preoperative planned screw direction of the angular-stable locking plates and the osteotomy planes were used for the intraoperative realization of the preoperative plan. There were seven opening wedge osteotomies and nine closing wedge (or single-cut) osteotomies performed. Eight-ten weeks postoperatively CT scans were obtained to assess bony consolidation and additionally used to generate a 3D model of the forearm. The simulated osteotomies- preoperative bone models with simulated correction - and the performed osteotomies - postoperative bone models - were analyzed for residual differences in 3D alignment.

Results: On average, a significant higher residual rotational deformity was observed in opening wedge osteotomies (8.30° ± 5.35°) compared to closing wedge osteotomies (3.47° ± 1.09°). The average residual translation was comparable small in both groups, i.e., below 1.5 mm and 1.1 mm for opening and closing wedge osteotomies, respectively.

Conclusions: The technique demonstrated high accuracy in performing closing wedge (or single-cut) osteotomies. However, for opening wedge osteotomies with extensive lengthening, probably due to the fact that precise reduction was difficult to achieve or maintain, the final corrections were less accurate.

No MeSH data available.


Related in: MedlinePlus