Corrective Osteotomies of Phalangeal and Metacarpal Malunions Using Patient-Specific Guides: CT-Based Evaluation of the Reduction Accuracy

Metacarpal and Phalangeal Malunions-Is It all About the Rotation?

Metacarpal and phalanx fractures are common injuries that can often be managed nonoperatively with satisfactory clinical outcomes. However, loss of normal finger alignment including malrotation and severe angulation as well as intra-articular deformities can lead to functional deficits which may benefit from operative intervention. There are numerous surgical options to correct malunions and the correct choice varies based on the injury pattern, concurrent injuries/complications, and surgeon's preference. While these surgeries can be technically demanding, successful treatment can lead to good results with satisfactory deformity correction and patient function.

Basal osteotomy of the first metacarpal using patient-specific guides and instrumentation: biomechanical and 3D CT-based analysis

INTRODUCTION

The aim of this study was to investigate the radiological outcomes of proximal closing metacarpal extension osteotomies using patient-specific guides and instruments (PSI) in early-stage trapeziometacarpal osteoarthritis to gain further insight into the joint loading surface and the benefits of the procedure.

METHODS

In a prospective observational study, nine patients were included between 11/2020 and 12/2021, undergoing a total of ten proximal metacarpal extension osteotomies for basal thumb osteoarthritis. Computer-assisted surgical planning was performed using computed tomography (CT) and three-dimensional (3D) segmentation, allowing the fabrication of 3D-printed PSIs for surgical treatment. Inclusion criteria were a 1-year follow-up by CT to assess postoperative correction of the positional shift of the first metacarpal (MC1) and the location of peak loads compared with the preoperative situation.

RESULTS

Radiographic analysis of the peak loading zone revealed a mean displacement on the articular surface of the trapezius of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to palmar, and on the articular surface of the MC1 of 0.4 mm ± 1.4 mm to radial and 0.1 mm ± 1.2 mm to dorsal.

CONCLUSION

There were trends indicating that a flatter pressure distribution and a dorsal shift of the peak loading zone may contribute to an improvement in subjective pain and patient satisfaction associated with this surgical procedure. The non-significant radiological results and the minor dorsal-radial shifts in our small study group limit a firm conclusion.

LEVEL OF EVIDENCE

III.

The Use of Patient-Specific Implants for the Treatment of Upper Extremity Fractures

In this article, we discuss the use of three-dimensional (3-D) printed patient-specific implants in the management of upper extremity fractures. Traditional fracture fixation methods involve the use of standard-sized implants, which may not adequately address the needs of every patient, particularly those who have complications related to fracture nonunion or malunion and those who have significant bone loss. The benefits and limitations of this technology are also discussed, along with considerations for implementation in clinical practice. Overall, the use of 3-D printed patient-specific implants holds promise for improving the accuracy and efficacy of upper extremity fracture management.

Automatic 3D Postoperative Evaluation of Complex Orthopaedic Interventions

In clinical practice, image-based postoperative evaluation is still performed without state-of-the-art computer methods, as these are not sufficiently automated. In this study we propose a fully automatic 3D postoperative outcome quantification method for the relevant steps of orthopaedic interventions on the example of Periacetabular Osteotomy of Ganz (PAO). A typical orthopaedic intervention involves cutting bone, anatomy manipulation and repositioning as well as implant placement. Our method includes a segmentation based deep learning approach for detection and quantification of the cuts. Furthermore, anatomy repositioning was quantified through a multi-step registration method, which entailed a coarse alignment of the pre- and postoperative CT images followed by a fine fragment alignment of the repositioned anatomy. Implant (i.e., screw) position was identified by 3D Hough transform for line detection combined with fast voxel traversal based on ray tracing. The feasibility of our approach was investigated on 27 interventions and compared against manually performed 3D outcome evaluations. The results show that our method can accurately assess the quality and accuracy of the surgery. Our evaluation of the fragment repositioning showed a cumulative error for the coarse and fine alignment of 2.1 mm. Our evaluation of screw placement accuracy resulted in a distance error of 1.32 mm for screw head location and an angular deviation of 1.1° for screw axis. As a next step we will explore generalisation capabilities by applying the method to different interventions.

3D planning and patient specific instrumentation for intraarticular corrective osteotomy of trapeziometacarpal-, metacarpal and finger joints

Background

Intra-articular malunions of the finger can lead to deformity and loss of function and can be treated with intra-articular corrective osteotomies. The aim of this study was to evaluate radiographic joint congruency, feasibility and functional outcome of three-dimensional (3D) printed patient-specific instrumentation (PSI) for corrective osteotomies at the trapeziometacarpal and finger joints.

Methods

Computer-tomography (CT) scans were acquired preoperatively for standard 3D planning, which was followed by calculation of cutting planes and the design of individualized bone surface contact drilling, sawing and reposition guides. Follow-up CT scans and clinical examinations (range of motion, grip strength) were performed. Postoperative complications were documented and patient-reported outcome measurements were assessed (Single Assessment Numeric Evaluation (SANE) score, brief Michigan Hand Questionnaire (MHQ)).

Results

Ten patients (mean age 28.4 ± 12.8,range 13.8–51.3) years) were included with a mean follow-up of 21 ± 18 (3–59) months including seven osteotomies at the trapeziometacarpal or metacarpophalangeal joints and three at the proximal interphalangeal joint (PIP). All radiographic follow-up examinations showed the planned correction with good joint congruency and regular osseous consolidation. At the latest follow-up, the range of motion (ROM) increased and the average grip strength recovered to the level of the contralateral side. No postoperative complication was detected. The mean SANE score improved from 44 ± 23 (0–70) to 82 ± 12 (60–90) after a mean of 72 ± 20 (44–114) months. The mean postoperative brief MHQ was 92 ± 8 (71–98).

Conclusion

The use of 3D PSI in treating intra-articular malunions at the trapeziometacarpal and finger joints restored articular congruency accurately. ROM and grip strength improved postoperatively comparable to the healthy contralateral side and patient-reported outcome measures improved after medium-term follow-up.

Intermediate-Term Outcome of 3-Dimensional Corrective Osteotomy for Malunited Distal Radius Fractures With a Mean Follow-Up of 6 Years

PURPOSE

Our study aimed to analyze the functional and radiological intermediate-term outcome of 3-dimensional-guided corrective osteotomies for malunited distal radius fractures and to evaluate the progression of osteoarthritis after this intervention.

METHODS

All patients with malunited distal radius fractures who underwent 3-dimensional-guided corrective osteotomies from October 2008 to January 2015 were included. Pre- and postoperative range of motion, grip strength, and postoperative patient-reported outcomes were assessed. Pre- and postoperative osteoarthritis grading was performed using conventional radiographs and the osteoarthritis grading system described by Knirk and Jupiter. Additionally, the evaluation of articular stepoff was performed using pre- and postoperative computed tomography.

RESULTS

Fifteen patients, with a mean follow-up of 6 years (range, 4.1-10.4 years), were included. According to rater 1, 8 cases had no postoperative osteoarthritis progression, 6 cases had progression of 1 grade, and 1 case had progression of 2 grades. According to rater 2, there was no progression in 11 cases, and there was progression of 1 grade in 2 cases and progression of 2 grades in 2 cases. Compared with before the surgery, the patients demonstrated a mean improvement of 14.8 kg (±12.6 kg) in grip strength after the surgery. At the last follow-up, the mean Patient-Rated Wrist Evaluation score was 11.8 (±12.0), the mean Disabilities of the Arm, Shoulder and Hand score was 11.1 (±11.4), and the mean residual pain score on the visual analog scale was 0.8 (±1.0).

CONCLUSIONS

The intermediate-term outcome of 3-dimensional-guided corrective osteotomies for distal radius intra-articular malunions showed excellent patient-reported outcomes and no clinically relevant progression of osteoarthritis.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Comparison of Lag Versus Nonlag Screw Fixation for Long Oblique Proximal Phalanx Fractures: A Biomechanical Study

PURPOSE

To compare lag versus nonlag screw fixation for long oblique proximal phalanx (P1) fractures in a cadaveric model of finger motion via the flexor and extensor tendons.

METHODS

We simulated long oblique P1 fractures with a 45° oblique cut in the index, middle, and ring fingers of 4 matched pairs of cadaveric hands for a total of 24 simulated fractures. Fractures were stabilized using 1 of 3 techniques: two 1.5-mm fully threaded bicortical screws using a lag technique, two 1.5-mm fully threaded bicortical nonlag screws, or 2 crossed 1.14-mm K-wires as a separate control. The fixation method was randomized for each of the 3 fractures per matched-pair hand, with each fixation being used in each hand and 8 total P1 fractures per fixation group. Hands were mounted to a custom frame where a computer-controlled, motor-driven, linear actuator powered movement of the flexor and extensor tendons. All fingers underwent 2,000 full flexion and extension cycles. Maximum interfragmentary displacement was continuously measured using a differential variable reluctance transducer. Our primary outcome was the difference in the mean P1 fragment displacement between lag and nonlag screw fixation at 2,000 cycles.

RESULTS

The observed differences in mean displacement between lag and nonlag screw fixation were not statistically significant throughout all time points. A two one-sided test procedure for paired samples confirmed statistical equivalence in the fragment displacement between these fixation methods at all time points, including the primary end point of 2,000 cycles.

CONCLUSIONS

Nonlag screws provided equivalent biomechanical stability to lag screws for simulated long oblique P1 fractures during cyclic testing in this cadaveric model.

CLINICAL RELEVANCE

Fixation of long oblique P1 fractures with nonlag screws has the potential to simplify treatment without sacrificing fracture stability during immediate postoperative range of motion.

Minimally Invasive Procedure for Correcting Extra-Articular Malunions of Metacarpals and Phalanges

PURPOSE

Extra-articular malunions of metacarpals and phalanges may cause palmar pain, finger scissoring, and splaying, and interfere with function. Current treatment involves open osteotomy and fixation with plates and screws. We present a minimally invasive method using cannulated headless screws for correction of malunions and examine the outcomes in a series of patients.

METHODS

Twenty malunions were operated on in 17 patients. In 16 cases, the malunion involved the metacarpal and in 4 it involved the proximal phalanx. All proximal phalanx and 3 metacarpal malunions were malrotation types, while the rest of the metacarpal malunions were dorsal angulations. The operation consisted of an opening wedge osteotomy in 8 patients; closing wedge osteotomy in 5; and a transverse osteotomy and derotation in the rest. Concomitant surgery to release tendon adhesions or contracted joints or to perform adipofascial flaps was performed in 8 cases. Fixation was achieved by means of a cannulated headless screw. Immediate range of motion was permitted in all cases.

RESULTS

Correction of the malunion and osteotomy union was achieved in all cases. One patient required manipulation of a digit that was found rotated at the first follow-up visit. Eleven fingers achieved more than 280° of total active motion. In 9 digits, the total active motion was less than 280° after the operation, yet improved 76° (range, 140°-30°) from their preoperative total active motion. The mean single-assessment numeric evaluation score for the whole group was 9.1.

CONCLUSIONS

The fixation provided by the cannulated headless screw is sufficient to permit immediate range of motion. Due to the minimal tissue disruption, this approach may be a reasonable alternative to the standard approach.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Morphological symmetry of the radius and ulna-Can contralateral forearm bones utilize as a reliable template for the opposite side?

The most important precondition for correction of the affected forearm using data from the contralateral side is that the left and right bone features must be similar, in order to develop patient-specific instruments (PSIs) and/or utilize computer-assisted orthopedic surgery (CAOS). The forearm has complex anatomical structure, and most people use their dominant hand more than their less dominant hand, sometimes resulting in asymmetry of the upper limbs. The aim of this study is to investigate differences of the bilateral forearm bones through a quantitative comparison of whole bone parameters including length, volume, bowing, and twisting parameters, and regional shape differences of the forearm bones. In total, 132 bilateral 3D radii and ulnae 3D models were obtained from CT images, whole bone parameters and regional shape were analyzed. Statistically significant differences in whole bone parameters were not shown. Regionally, the radius shows asymmetry in the upper section of the central part to the upper section of the distal part. The ulna shows asymmetry in the lower section of the proximal part to the lower section of the central part. Utilizing contralateral side forearm bones to correct the affected side may be feasible despite regional differences in the forearm bones of around 0.5 mm.

Minimally Invasive Intramedullary Screw Versus Plate Fixation for Proximal Phalanx Fractures: A Biomechanical Study

PURPOSE

To compare the maximum interfragmentary displacement of short oblique proximal phalanx (P1) fractures fixed with an intramedullary headless compression screw (IMHCS) versus a plate-and-screws construct in a cadaveric model that generates finger motion via the flexor and extensor tendons of the fingers.

METHODS

We created a 30° oblique cut in 24 P1s of the index, middle, ring, and little fingers for 3 matched pairs of cadaveric hands. Twelve fractures were stabilized with an IMHCS using an antegrade, dorsal articular margin technique at the P1 base. The 12 matched-pair P1 fractures were stabilized with a radially placed 2.0-mm plate with 2 bicortical nonlocking screws on each side of the fracture. Hands were mounted to a frame allowing a computer-controlled, motor-driven, linear actuator powered movement of fingers via the flexor and extensor tendons. All fingers underwent 2,000 full-flexion and extension cycles. Maximum interfragmentary displacement was continuously measured using a differential variable reluctance transducer.

RESULTS

The observed mean displacement differences between IMHCS and plate-and-screws fixation was not statistically significant throughout all time points during the 2,000 cycles. A 2 one-sided test procedure for paired samples confirmed statistical equivalence in fracture displacement between fixation methods at the final 2,000-cycle time point.

CONCLUSIONS

The IMHCS provided biomechanical stability equivalent to plate-and-screws for short oblique P1 fractures at the 2,000-cycle mark in this cadaveric model.

CLINICAL RELEVANCE

Short oblique P1 fracture fixation with an IMHCS may provide adequate stability to withstand immediate postoperative active range of motion therapy.

The Accuracy of Three-Dimensional Planned Bone Tumor Resection Using Patient-Specific Instrument

Introduction

Although treatment of bone tumors is multidisciplinary, the complete surgical resection of bone tumors remains the mainstay of the treatment. Patient-specific instruments (PSI) are personalized tools, which help the surgeon to perform tumor resections accurately. The aim of this study is to evaluate how precise the planned resection can be intraoperatively executed with the use of PSI.

Patients and Methods

Eleven patients who underwent a resection of bone tumor using PSI were analyzed. A preoperative model of the tumor and the affected bone was created from acquired CT scans and MRI. After defining the resection planes, PSI were produced by a 3D printer. The resected piece of bone was scanned and imported in the original planning model enabling the assessment of the distance between the planned resection plane and the realized osteotomy in every direction.

Results

In overall, the combined error of an osteotomy ranges from 0.74 ± 0.96 mm to 3.60 ± 2.46 mm. The average errors observed in situations with one resection plane (simple osteotomy) are lower than in complex curved osteotomies with multiple planes, in which we also found a greater variance.

Conclusion

3D planned bone tumor resections using PSI show promising results for precise resection at different anatomical regions. Even if the found error range in this series is slightly higher than reported, PSI remain a valuable tool to facilitate complex bone tumor resections.

Recent advances in the surgical treatment of malunions in hand and forearm using three-dimensional planning and patient-specific instruments

Malunions of the forearm and hand cause significant disability. Moreover, intraarticular deformities may contribute to early onset osteoarthritis. Such conditions require precise surgical correction in order to improve functional outcomes and prevent early or late complications. The purpose of this study was to describe the technical advantages of accurate anatomical reconstruction using 3D guided osteotomies and patient specific instruments (PSI) in multiple joints of the hand and forearm. Acquisition of three-dimensional (3D) datasets and surgical implementation of PSI was performed in a series of patients between December 2014 and July 2017. Patients had intra- or extra-articular malunions of the forearm, radiocarpal joint, trapeziometacarpal joint, or proximal interphalangeal joint. A previously described 3D surface model that incorporates CT data was used for segmentation (Mimics®, Materialise™, Belgium). For all the cases, CT scans of both forearms were acquired to use the contralateral uninjured side as the anatomic reconstruction template. Computer-assisted assessment of the deformity, the preoperative plan, and the design of PSI are described. Outcomes were determined by evaluating step-off correction, fusion, changes in range of motion (ROM) and grip strength. Six patients were included in the study; all achieved fusion. Improved clinical outcomes including pain reduction, better ROM and grip strength were obtained. Complete correction of intraarticular step-off was achieved in all cases with intraarticular malunions. 3D guided osteotomies are an established surgical treatment option for malunions of the hand and forearm. 3D analysis is a helpful diagnostic tool that provides detailed information about the underlying deformity. PSI can be developed and used for surgical correction with maximal accuracy for both intraarticular step-off and angular deformity.

Patient-Specific Surgical Guidance System for Intelligent Orthopaedics

Clinical benefits for image-guided orthopaedic surgical systems are often measured in improved accuracy and precision of tool trajectories, prosthesis component positions and/or reduction of revision rate. However, with an ever-increasing demand for orthopaedic procedures, especially joint replacements, the ability to increase the number of surgeries, as well as lowering the costs per surgery, is generating a similar interest in the evaluation of image-guided orthopaedic systems. Patient-specific instrument guidance has recently gained popularity in various orthopaedic applications. Studies have shown that these guides are comparable to traditional image-guided systems with respect to accuracy and precision of the navigation of tool trajectories and/or prosthesis component positioning. Additionally, reports have shown that these single-use instruments also improve operating room management and reduce surgical time and costs. In this chapter, we discuss how patient-specific instrument guidance provides benefits to patients as well as to the health-care community for various orthopaedic applications.

Standardization of torsional CT measurements of the lower limbs with threshold values for corrective osteotomy

INTRODUCTION

Re-establishing anatomic rotational alignment of shaft fractures of the lower extremities remains challenging. Clinical evaluation in combination with radiological measurements is important in pre- and post-surgical assessment. Based on computed tomography (CT), a range of reference values for femoral torsion (FT) and tibial torsion (TT) have historically been reported, which require standardization to optimize the significant intra- and inter-observer variability. The aims of this study were (re-)evaluation of the reference FT and TT angles, determination of the normal intra-individual side-to-side torsional differences to aid the surgical decision-making process for reoperation, and development of a novel 3D measurement method for FT.

MATERIALS AND METHODS

In this retrospective study, we included 55 patients, without any known torsional deformities of the lower extremities. Two radiologists, independently, measured the rotational profile of the femora using the Hernandez and Weiner CT methods for FT, and the tibiae using the bimalleolar method for TT. The intra-individual side-to-side difference in paired femora and paired tibiae was determined. A 3D technique for FT assessment using InSpace^® was designed.

RESULTS

FT and TT demographic values were lower than previously reported, with mean FT values of 5.1°-8.8° and mean TT values of 25.5°-27.7°. Maximal side-to-side differences were 12°-13° for FT and 12° for TT. The Weiner method for FT was less variable than the Hernandez method. The new 3D method was equivocal to the conventional CT measurements.

CONCLUSION

The results from this study showed that the maximal side-to-side tolerance in asymptomatic normal adult lower extremities is 12°-13° for FT and 12° for TT, which could be a useful threshold for surgeons as indication for revision surgery (e.g., derotational osteotomy). We developed a new 3D CT method for FT measurement which is similar to 2D and could be used in the future for virtual 3D planning.