Purpose To analyze the feasibility of combining computer-assisted 3-dimensional planning with patient-specific drill guides and to evaluate this technology's surgical outcomes for distal radius ...intra-articular malunions. Methods Six symptomatic patients with intra-articular malunions of the distal radius with a stepoff of more than 2 mm were treated with an outside-in corrective osteotomy. The described cases consist of 2 malunited volar Barton fractures, 2 radial styloid fractures, 1 AO-type C1 fracture, and 1 die-punch fracture. The osteotomies were guided by 3-dimensionally generated aiming guides that allowed precise cutting and the reduction of up to 2 fragments. All 6 patients were examined clinically and radiologically after 1 year. The surgical outcomes were quantitatively analyzed by comparing the preoperative and postoperative computed tomographic data. Results In all 6 cases, the osteotomies were consolidated 8 weeks postoperatively. After 1 year, 4 patients were pain-free, 1 had mild pain, and 1 experienced moderate pain during heavy work. Wrist motion and grip strength were improved in all patients. The postoperative radiographs showed no articular stepoff or degenerative changes. Conclusions Patient-specific aiming guides provided a reliable method to correct intra-articular malunions of the distal radius. This technique allows the surgeon to safely perform difficult intra-articular osteotomies and may help limit the need for salvage procedures such as partial or complete wrist arthrodesis. Type of study/level of evidence Therapeutic IV.
Background Corrective osteotomies of malunited fractures of the proximal and distal humerus are among the most demanding orthopedic procedures. Whereas the restoration of the normal humeral anatomy ...is the ultimate goal, the quantification of the deformity as well as the transfer of the preoperative plan is challenging. The purpose of this study was to provide a guideline for 3-dimensional (3D) corrective osteotomies of malunited intra-articular fractures of the humerus and a detailed overview of existing and novel instruments to enlarge the toolkit for 3D preoperative planning and intraoperative realization using patient-specific guides. Methods We describe the preoperative 3D deformity analysis, relevant considerations for the preoperative plan, design of the patient-specific guides, and surgical technique of corrective osteotomies of the humerus. Results The presented technique demonstrates the benefit of computer-assisted surgery for complex osteotomies of the humerus from a preoperative deformity analysis to the creation of feasible surgical procedures and the generation of patient-specific guides. Conclusions A 3D analysis of a post-traumatic deformity of the humerus, 3D preoperative planning, and use of patient-specific guides facilitate corrective osteotomies of complex malunited humeral fractures.
Purpose To present results regarding the accuracy of the reduction of surgically reconstructed scaphoid nonunions or fractures using 3-dimensional computer-based planning with and without ...patient-specific guides. Methods Computer-based surgical planning was performed with computed tomography (CT) data on 22 patients comparing models of the pathological and the opposite uninjured scaphoid in 3 dimensions. For group 1 (9 patients), patient-specific guides were designed and manufactured using additive manufacturing technology. During surgery, the guides were used to define the orientation of the reduced fragments. The scaphoids in group 2 (13 patients) were reduced with the conventional freehand technique. All scaphoids in both groups were fixed with a headless compression screw or K-wires, and all bone defects (except one) were filled with autologous bone grafts or vascularized grafts. Postoperative CT scans were acquired 2 or more months after the operations to monitor consolidation and compare the final result with the preoperative plan. The clinical results and accuracy of the reconstructions were compared. Results In group 1, 8 of 9 scaphoids healed after 2 to 6 months, and partial nonunion after 9 months was observed in one patient. In group 2, 11 of 13 scaphoids healed between 2 and 34 months whereas 2 scaphoids did not consolidate. Comparison of the preoperative and postoperative 3-dimensional data revealed an average residual displacement of 7° (4° in flexion-extension, 4° in ulnar-radial deviation, and 3° in pronation-supination) in group 1. In group 2, residual displacement after surgery was 26° (22° in flexion-extension, 12° in ulnar-radial deviation, and 7° in pronation-supination). The difference in the accuracy of reconstruction was significant. Conclusions Although the scaphoid is small, patient-specific guides can be used to perform scaphoid reconstructions. When the guides were used, the reconstructions were significantly more anatomic compared with those resulting from the freehand technique. Type of study/level of evidence Therapeutic III.
Background In the presence of severe osteoarthritis, osteonecrosis, or proximal humeral fracture, the contralateral humerus may serve as a template for the 3-dimensional (3D) preoperative planning of ...reconstructive surgery. The purpose of this study was to develop algorithms for performing 3D measurements of the humeral anatomy and further to assess side-to-side (bilateral) differences in humeral head retrotorsion, humeral head inclination, humeral length, and humeral head radius and height. Methods The 3D models of 140 paired humeri (70 cadavers) were extracted from computed tomographic data. Geometric characteristics quantifying the humeral anatomy in 3D were determined in a semiautomatic fashion using the developed computer algorithms. The results between the sides were compared for evaluating bilateral differences. Results The mean bilateral difference of the humeral retrotorsion angle was 6.7° (standard deviation SD, 5.7°; range, −15.1° to 24.0°; P = .063); the mean side difference of the humeral head inclination angle was 2.3° (SD, 1.8°; range, −5.1° to 8.4°; P = .12). The side difference in humeral length (mean, 2.9 mm; SD, 2.5 mm; range, −8.7 mm to 10.1 mm; P = .04) was significant. The mean side difference in the head sphere radius was 0.5 mm (SD, 0.6 mm; range, −3.2 mm to 2.2 mm; P = .76), and the mean side difference in humeral head height was 0.8 mm (SD, 0.6 mm; range, −2.4 mm to 2.4 mm; P = .44). Conclusions The contralateral anatomy may serve as a reliable reconstruction template for humeral length, humeral head radius, and humeral head height if it is analyzed with 3D algorithms. In contrast, determining humeral head retrotorsion and humeral head inclination from the contralateral anatomy may be more prone to error.
Purpose To virtually assess nonunions of the scaphoid waist using 3-dimensional computed tomography (CT) reconstruction for the amount of displacement of the distal fragment and the postfracture ...reduction position using the intact opposite scaphoid for reference. Methods We generated 3-dimensional reconstructions for 11 nonunions of the scaphoid waist and the contralateral intact scaphoids based on CT. The mean age of the patients was 25 years and the time from injury to the CT scan was 2.4 years. We used the mirrored 3-dimensional model of the healthy scaphoid to guide virtual reduction of the nonunion and calculated the amount of displacement of the distal pole fragment from prereduction to postreduction. We compared the results with the intrascaphoid angles calculated using single CT slices. Results The scaphoid nonunions showed a mean flexion deformity of 23°, an ulnar deviation of 5°, and a pronation deformity of 10°. Mean translation was 0.9 mm volarward, 0.2 mm radialward, and 3.3 mm distalward. After reduction, all scaphoids showed a bony overlap on the dorsoradial side; the mean volume of this region was 3% of total bone volume. There was no correlation between the degree of displacement and the intrascaphoid angle measurements. Conclusions Preoperative planning for scaphoid reconstruction is usually performed using conventional radiographs and single CT slices. However, by synthesizing the information from the CT into a 3-dimensional reconstruction, an exact analysis is possible. This method also allows quantification of prosupination displacement. The postreduction area of dorsal bone overlap may be due to appositional callus formation. Clinical relevance Simple volar opening of the scaphoid allows correction of angulation deformities but results in lengthening of the scaphoid. Correct reduction of the scaphoid fragments is often only possible if the dorsal appositional callus is resected.
Purpose Accuracy and feasibility of corrective osteotomies using 3-dimensional planning tools and patient-specific instrumentation has been reported by multiple authors with promising results. ...However, studies describing clinical outcomes following these procedures are rare. Therefore, the purpose of this study was to compare the results of computer-assisted corrective osteotomies of the diaphyseal and distal radius with a conventional non–computer-assisted technique regarding duration of surgery, consolidation of the osteotomy, and complications. Also, subjective and objective clinical outcome parameters were assessed. Methods We retrospectively compared the results of 31 patients who underwent a corrective osteotomy performed conventionally with 25 patients treated with a computer-assisted method (CA) using patient-specific instrumentation. Baseline data were similar among both groups. The duration of surgery, bony consolidation, complications, gain in range of motion, and subjective outcome were recorded. Results The mean operating time was significantly shorter in the CA group compared with the conventional group. After 12 weeks, significantly more osteotomies were considered healed in the CA group compared with the conventional group. Two patients in the CA group required revision surgery to treat nonunion of the osteotomy. Otherwise clinical results were similar among both groups. Conclusions The results demonstrate that the computer-assisted method facilitates shorter operation times while providing similar clinical results. Type of study/level of evidence Therapeutic IV.
Background The surgical treatment of malunions after midshaft clavicle fractures is associated with a number of potential complications and the surgical procedure is challenging. However, with ...appropriate and meticulous preoperative surgical planning, the surgical correction yields satisfactory results. The purpose of this study was to provide a guideline and detailed overview for the computer-assisted planning and 3-dimensional (3D) correction of malunions of the clavicle. Methods The 3D bone surface models of the pathologic and contralateral sides were created on the basis of computed tomography data. The computer-assisted assessment of the deformity, the preoperative plan, and the design of patient-specific guides enabling compression plating are described. Results We demonstrate the benefit and versatility of computer-assisted planning for corrective osteotomies of malunions of the midshaft clavicle. In combination with patient-specific guides and compression plating technique, the correction can be performed in a more standardized fashion. We describe the determination of the contact-optimized osteotomy plane. An osteotomy along this plane facilitates the correction and enlarges the contact between the fragments at once. We further developed a technique of a stepped osteotomy that is based on the calculation of the contact-optimized osteotomy plane. The stepped osteotomy enables the length to be restored without the need of structural bone graft. The application of the stepped osteotomy is presented for malunions of the clavicle with shortening and excessive callus formation. Conclusions The 3D preoperative planning and patient-specific guides for corrective osteotomies of the clavicle may help reduce the number of potential complications and yield results that are more predictable.
There is evidence that specific variants of scapular morphology are associated with dynamic and static posterior shoulder instability. To this date, observations regarding glenoid and/or acromial ...variants were analyzed independently, with two-dimensional imaging or without comparison with a healthy control group. Therefore, the purpose of this study was to analyze and describe the three-dimensional (3D) shape of the scapula in healthy and in shoulders with static or dynamic posterior instability using 3D surface models and 3D measurement methods.
In this study, 30 patients with unidirectional posterior instability and 20 patients with static posterior humeral head subluxation (static posterior instability, Walch B1) were analyzed. Both cohorts were compared with a control group of 40 patients with stable, centered shoulders and without any clinical symptoms. 3D surface models were obtained through segmentation of computed tomography images and 3D measurements were performed for glenoid (version and inclination) and acromion (tilt, coverage, height).
Overall, the scapulae of patients with dynamic and static instability differed only marginally among themselves. Compared with the control group, the glenoid was 2.5° (P = .032), respectively, 5.7° (P = .001) more retroverted and 2.9° (P = .025), respectively, 3.7° (P = .014) more downward tilted in dynamic, respectively, static instability. The acromial roof of dynamic instability was significantly higher and on average 6.2° (P = .007) less posterior covering with an increased posterior acromial height of +4.8mm (P = .001). The acromial roof of static instability was on average 4.8° (P = .041) more externally rotated (axial tilt), 7.3° (P = .004) flatter (sagittal tilt), 8.3° (P = .001) less posterior covered with an increased posterior acromial height of +5.8 mm (0.001).
The scapula of shoulders with dynamic and static posterior instability is characterized by an increased glenoid retroversion and an acromion that is shorter posterolaterally, higher, and more horizontal in the sagittal plane. All these deviations from the normal scapula values were more pronounced in static posterior instability.
Category:
Midfoot/Forefoot
Introduction/Purpose:
Recent studies have shown that Hallux valgus deformity can lead to transfermetatarsalgia due to an impairment and relative shortening of the first ...ray. During ReveL osteotomy the relative shortening of the MT I is not addressed. Furthermore, a posterior deviation of the osteotomy angle results in additional iatrogenic shortening of the MT I and might favor postoperative transfermetatarsalgia.
Methods:
A 3-dimensional model of a foot was obtained from CT scans of a cadaveric foot.
The MT I of the 3-dimensional model was then pivoted medially to simulate a severe hallux valgus deformity of an intermetatarsal angle (IMA) of 18° and an intermediate hallux valgus deformity of an IMA of 13°.
A ReveL operation was simulated to correct the IMA to 8° for the severe and the intermediate Hallux valgus. Therefore the osteotomy angle in the coronal plane (f=0) was chosen perpendicular to the axis of the second metatarsalia. Afterwards the length of MT I was measured. This procedure was repeated for an posterior altered osteotomy angle (f = 5°,10°, 15° and 20°).
Results:
The change in MT I length resulting from an osteotomy perpendicular to the axis of MT II was 0.6 mm for a severe hallux valgus (IMA correction from 18° to IMA 8°) and 0.3 mm for a moderate hallux valgus (IMA 13° to IMA 8°). A posterior deviation of the osteotomy angle led to additional shortening (max. 2.9 mm) with a total shortening of up to 3.5 mm (Figure 3). To avoid any shortening of MT I an osteotomy slightly pointing anterior (negative f) of 3.5° (IMA change of 10°) and 3° (IMA change of 5°) was found.
Conclusion:
ReveL procedure led only to a maximum shortening of 3.5 mm for a posterior deviation of 20°. Considering recently described MT I length cut off values of 2-3 mm for avoiding transfermetatarsalgia the osteotomy should be performed within an anterior directed cut angle of 4° and a posterior directed cut angle of 10° for the correction of a severe hallux valgus. However, further studies are needed to investigate the clinical impact of our findings.
Category:
Bunion
Introduction/Purpose:
An optimal osteotomy angle can avoid shortening of the first metatarsal bone after hallux valgus surgery and therefore reduce the risk of ...transfer-metatarsalgia. Up to date the osteotomy is performed free-hand without guidance and is therefore prone to unwanted variability in accuracy. The purpose of the present ex-vivo study was to investigate whether overlaying a hologram (augmented reality, AR) would improve accuracy of the distal osteotomy during hallux valgus surgery.
Methods:
A polyamide foot skeleton was constructed based a CT scan of a cadaveric foot and covered with medical silicon soft tissue. Three different polyamide first metatarsals were inserted to simulate a light, moderate and severe hallux valgus deformity. Distal Osteotomies of the first metatarsals were performed by two surgeons with different levels of surgical experience each with (AR, n=15x2) or without (controls, n=15x2) overlay of a hologram depicting an angle of osteotomy perpendicular to the second metatarsal in the transverse plane. Subsequently, the deviation to the plumb line of the second metatarsal in the transverse plane of all 60 osteotomies angles were optically measured and statistically analyzed.
Results:
Overall, the AR-guided osteotomies were more accurate (4.9 ± 4.2°) compared to the freehand cuts (6.7± 6.1°) by tendency (p=0.2). However, while the inexperienced surgeon performed more accurate osteotomies with AR with a mean angle of 6.4± 3.5° compared to freehand 10.5 ± 5.5° (p=0.02), no significant difference was noticed for the experienced surgeon with an osteotomy angle of around 3° in both cases.
Conclusion:
This pilot-study suggests that augmented reality guided osteotomies can potentially improve accuracy during hallux valgus surgery, particularly for less experienced surgeons. However, clinical studies are needed to investigate the clinical benefit of augmented reality in hallux valgus surgery.
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