Use Of Patient-specific Instrumentation Research Articles

Efficiency assessment of intelligent patient-specific instrumentation in total knee arthroplasty: a prospective randomized controlled trial

BackgroundIn total knee arthroplasty (TKA), the practical use of patient-specific instrumentation (PSI) has been reported previously with both advantage and disadvantage. The application of artificial intelligent (AI) forces overwhelmingly development of medical industries, while the impact of AI on PSI efficiency remains unknown. Thus, this study aimed to assess the efficiency of Intelligent-PSI (i-PSI) in TKA, compared with the conventional instrumentation-TKA (CI).Methods102 late-stage OA patients who met inclusive criteria were recruited in this prospective randomized controlled trial and separated into two groups (i-PSI vs. CI). In both groups, an AI preoperative planning engine was applied for surgery decision making. In CI group, conventional instrumentation was applied for bony resection, while resection of i-PSI group was completed with i-PSI. A convolutional neural network was applied to automatically process computer tomography images and thus produced i-PSI. With the help of three-dimension printing, the workflow of production was largely simplified. AI-driven preoperative planning guided resection and alignment decisions. Resection measurement, perioperative radiography and perioperative clinical outcomes were analyzed to verify efficiency of i-PSI.ResultsIn resection outcomes, smaller deviation of lateral and medial distal femoral resection were found in i-PSI group than CI group (P = 0.032 and 0.035), while no difference was found in other resection planes. In radiography outcomes, postoperative coronal alignments of i-PSI group, including postoperative Hip–knee–ankle axis (HKA) (P = 0.025), postoperative HKA outliners (P = 0.042), Femoral coronal alignment (FCA) (P = 0.019) and Joint line convergence angle (JLCA) (P = 0.043) showed closer to neutral position than CI group. Moreover, Femoral sagittal alignment (FSA) of i-PSI group showed closer to neutral position than CI group(P = 0.005). No difference was found in other alignments. In clinical outcomes, i-PSI group seemed to cost more surgical time than CI group (P = 0.027), while others showed no differences between the two groups.ConclusionIntelligent Patient-specific Instrumentation in TKA achieved simplified production flow than conventional PSI, while also showed more accurate resection, improved synthesis position and limb alignment than conventional instrumentation. Above all, this study proved that i-PSI being an applicable and promising tool in TKA.

Step-cut osteotomy for cubitus varus deformity with application of patient-specific instrument in children: a preliminary report.

The step-cut osteotomy has been recognized as a valuable approach for addressing cubitus varus deformity, albeit one that necessitates technical proficiency. This study aims to evaluate the efficacy of the modified step-cut osteotomy technique in conjunction with patient-specific instruments by clinical and radiological assessment. We conducted a retrospective review of patients who underwent modified step-cut osteotomy with the use of patient-specific instruments in conjunction with Kirschner wires fixation for the correction of cubitus varus deformity between April 2016 and April 2022. Follow-up was performed for a minimum of two years, during which pre-operative and post-operative clinical and radiological parameters were compared. Fifteen patients were enrolled in this study. The mean pre-operative humeral-elbow-wrist (HEW) of the affected side was -21.7° (ranging from -14° to -34°), while the normal side was 9.4° (ranging from 5° to 15°). The post-operation HEW of affected side was 9° (ranging from 4° to 16°). There was no significant difference between the normal side and affected side after operation (p = 0.74). Pre-operative range of motion in the affected side was 130°, while the post-operative range of motion was 132°. Fourteen patients (93.3%) were pleased with the overall appearance of their elbow. None lazy-S deformity was observed in these cases. There were no major complications. The modified step-cut osteotomy technique, utilizing patient-specific instrument in conjunction with Kirschner wires fixation was found to be a safe, reliable, and technically easy procedure for correcting cubitus varus deformity.

Internal hemipelvectomy: A single institution's learning curve and longitudinal experience.

Wide margin resection for pelvic tumors via internal hemipelvectomy is among the most technically challenging procedures in orthopedic oncology. As such, surgeon experience and technique invariably affect patient outcomes. The aim of this clinical study was to assess how an individual surgeon's experiences and advancements in technology and techniques in the treatment of internal hemipelvectomy have impacted patient outcomes at our institution. This study retrospectively examined a single tertiary academic institution's consecutive longitudinal experience with internal hemipelvectomy for primary sarcoma or pelvic metastases over a 26-year period between the years 1994 and 2020. Outcomes were assessed using two separate techniques. The first stratified patients into cohorts based on the date of surgery with three distinct "eras" ("early," "middle," and "modern"), which reflect the implementation of new techniques, including three-dimensional (3D) computer navigation and cutting guide technology into our clinical practice. The second method of cohort selection grouped patients based on each surgeon's case experience with internal hemipelvectomy ("inexperienced," "developing," and "experienced"). Primary endpoints included margin status, complication profiles, and long-term oncologic outcomes. Whole group multivariate analysis was used to evaluate variables predicting blood loss, operative time, tumor-free survival, and mortality. A total of 72 patients who underwent internal hemipelvectomy were identified. Of these patients, 24 had surgery between 1994 and 2007 (early), 28 between 2007 and 2015 (middle), and 20 between 2016 and 2020 (modern). Twenty-eight patients had surgery while the surgeon was still inexperienced, 24 while developing, and 20 when experienced. Evaluation by era demonstrated that a greater proportion of patients were indicated for surgery for oligometastatic disease in the modern era (0% vs. 14.3% vs. 35%, p = 0.022). Fewer modern cases utilized freehand resection (100% vs. 75% vs. 55%, p = 0.012), while instead opting for more frequent utilization of computer navigation (0% vs. 25% vs. 20%, p = 0.012), and customized 3D-printed cutting guides (0% vs. 0% vs. 25%, p = 0.002). Similarly, there was a decline in the rate of massive blood loss observed (72.2% vs. 30.8% vs. 35%, p = 0.016), and interdisciplinary collaboration with a general surgeon for pelvic dissection became more common (4.2% vs. 32.1% vs. 85%, p < 0.001). Local recurrence was less prevalent in patients treated in middle and modern eras (50% vs. 15.4% vs. 25%, p = 0.045). When stratifying by case experience, surgeries performed by experienced surgeons were less frequently complicated by massive blood loss (66.7% vs. 40% vs. 20%, p = 0.007) and more often involved a general surgeon for pelvic dissection (17.9% vs. 37.5% vs. 65%, p = 0.004). Whole group multivariate analysis demonstrated that the use of patient-specific instrumentation (PSI) predicted lower intraoperative blood loss (p = 0.040). However, surgeon experience had no significant effect on operative time (p = 0.125), tumor-free survival (p = 0.501), or overall patient survival (p = 0.735). While our institution continues to utilize neoadjuvant and adjuvant therapies following current guideline-based care, we have noticed changing trends from early to modern periods. With the advent of new technologies, we have seen a decline in freehand resections for hemipelvectomy procedures, and a transition to utilizing more 3D navigation and customized 3D cutting guides. Furthermore, we have employed the use of an interdisciplinary team approach more regularly for these complicated cases. Although our results do not demonstrate a significant change in perioperative outcomes over the years, our institution's willingness to treat more complex cases likely obscures the benefits of surgeon experience and recent technological advances for patient outcomes.

3-dimensionally printed patient-specific glenoid drill guides vs. standard nonspecific instrumentation: a randomized controlled trial comparing the accuracy of glenoid component placement in anatomic total shoulder arthroplasty

Traditional, commercially-sourced patient-specific instrumentation (PSI) systems for shoulder arthroplasty improve glenoid component placement but can involve considerable cost and outsourcing delays. The purpose of this randomized controlled trial was to compare the accuracy of glenoid component positioning in anatomic total shoulder arthroplasty (aTSA) using an in-house, point-of-care, 3-dimensionally (3D) printed patient-specific glenoid drill guide versus standard non-specific instrumentation. This single-center randomized controlled trial included 36 adult patients undergoing primary aTSA. Patients were blinded and randomized 1:1 to either the PSI or the standard aTSA guide groups. The primary endpoint was accuracy of glenoid component placement (version and inclination), which was determined using a metal-suppression CT scan taken between 6 weeks to 1 year postoperatively. Deviation from the preoperative 3D templating plan was calculated for each patient. Blinded postoperative CT measurements were performed by a fellowship-trained shoulder surgeon and a musculoskeletal radiologist. Nineteen patients were randomized to the patient-specific glenoid drill guide group, and 17 were allocated to the standard instrumentation control group. There were no significant differences between the two groups for native version (p = 0.527) or inclination (p = 0.415). The version correction was similar between the two groups (p = 0.551), and the PSI group was significantly more accurate when correcting version than the control group (p = 0.042). The PSI group required a significantly greater inclination correction than the control group (p = 0.002); however, the two groups still had similar accuracy when correcting inclination (p = 0.851). For the PSI group, there was no correlation between accuracy of component placement and native version, native inclination, or Walch classification of glenoid wear (p > 0.05). For the control group, accuracy when correcting version was inversely correlated with native version (p = 0.033), but accuracy was not correlated with native inclination or Walch classification of glenoid wear (p > 0.05). The intraclass correlation coefficient (ICC) was 0.703 and 0.848 when measuring version and inclination accuracy respectively. When compared to standard instrumentation, the use of in-house, 3D-printed, patient-specific glenoid drill guides during aTSA led to more accurate glenoid component version correction and similarly accurate inclination correction. Additional research should examine the influence of proper component position and use of patient-specific instrumentation on clinical outcomes.

Osteotomies around the knee: preoperative planning using CT-based three-dimensional analysis, patient-specific cutting and reduction guides

The goal of osteotomy is either to restore pretraumatic anatomic conditions or to shift the load to less affected compartments. Indications for computer-assisted 3D analysis and the use of patient-specific osteotomy and reduction guides include "simple" deformities and, in particular, multidimensional complex (especially posttraumatic) deformities. General contraindications for performing acomputed tomography (CT) scan or for an open approach for performing the surgery. Based on CT examinations of the affected and, if necessary, the contralateral healthy extremity as ahealthy template (including hip, knee, and ankle joints), 3D computer models are generated, which are used for 3D analysis of the deformity as well as for calculation of the correction parameters. For the exact and simplified intraoperative implementation of the preoperative plan, individualized guides for the osteotomy and the reduction are produced by 3D printing. Partial weight-bearing from the first postoperative day. Increasing load after the first x‑ray control 6weeks postoperatively. No limitation of the range of motion. There are several studies that have analyzed the accuracy of the implementation of the planned correction for corrective osteotomies around the knee joint with the use of patient-specific instruments with promising results.

Patient Specific Instrumentation and Total Ankle Arthroplasty

Category: Ankle Arthritis; Ankle Introduction/Purpose: Total Ankle Arthroplasty (TAA) can now be performed using Patient Specific Instrumentation (PSI). Advantages include the ability to pre-operatively plan bone resections and implant position and reduce the number of intra- operative surgical steps. The aim of this study was to compare PSI with Standard Instrumentation (SI) in a non-randomised retrospective cohort study with respect to patient reported outcomes, tourniquet time, fluoroscopy time and post-operative alignment. Methods: 159 patients (111 male, 48 female) undergoing a total of 168 INFINITY TAA using PSI (Prophecy, Wright Medical Technology) or SI between 2014 and 2020 were included with a minimum follow up of 12 months. Patient reported outcome measures (PROMS) were obtained pre-operatively and at one year and included the Manchester-Oxford Foot Questionnaire (MOXFQ), Ankle Osteoarthritis Scale (AOS) and EQ-5D Index. Coronal plane deformity correction was assessed using the midline tibiotalar angle (MTTA). Demographics, tourniquet time and intra-operative fluoroscopy times were obtained from the hospital records. Results: There were 106 TAA in the SI group and 62 TAA in the PSI group. The was no significant difference in total MOXFQ, AOS or EQ5D. There was however a significant difference (p=.032) in favour of PSI in the walking/standing domain of the MOXFQ at 12 months. There was a significantly reduced tourniquet time (PSI mean: 95.39 mins, SI mean: 116.87 mins, p&lt;.001) and radiation exposure (PSI mean: 31 seconds, SI mean: 53 seconds, p&lt;.001). Angular correction was more accurate in the PSI group (PSI mean: 1.29°, SI mean: 2.26°, p=.005). Conclusion: This study supports the use of patient specific instrumentation to decrease operative time, reduce intraoperative fluoroscopy and improve accuracy of implantation in TAA. The walking/standing domain of the MOXFQ has been shown to be the most sensitive to change and in this study demonstrated a further potential benefit.

Use of 3D-Printed Patient Specific Guides in Osteotomies around the Knee

High tibial osteotomies are challenging procedures that have traditionally implemented two-dimensional planning (2D) for a complex three-dimensional surgery (3D). In an effort to improve the accuracy and precision of the technique, there has been a growing interest in the use of patient specific instrumentation (PSI). The implementation of PSI in osteotomies has demonstrated consistent and reliable results in the correction of the hip-knee-ankle angle, proximal tibial angle, and the posterior tibial slope. Initial clinical studies describing the implementation of this technology have reported superior accuracy in both the coronal and sagittal planes as compared to free-hand techniques. Additionally, these studies reported a fast surgeon learning curve, short operative times, and minimal fluoroscopy exposure. The senior author's preferred closing wedge HTO technique utilizes a patient specific cutting guide with osteotomy fixation provided by an extra-cortical titanium alloy locking plate. This technique is designed to provide reliable and accurate HTOs while minimizing the risk of major complications such as hinge fractures on the contralateral cortex.

Intercalary and geographic lower limb tumor resections with the use of 3D printed Patient Specific Instruments- when less is more

BackgroundPrimary bone sarcomas are associated with critically sized bone defects and require complete resection with negative margins. Recent advancements in health care have pioneered novel approaches such as the implementation of 3D surgical technologies. This study presents oncological and functional outcomes following tumor resections of long bones with the use of customized 3D-printed Patient Specific Instruments (PSIs). MethodsThis single-center retrospective study is comprised of seventeen patients who underwent either intercalary (N = 12) or geographic (N = 5) resections with various reconstruction methods including allograft (N = 8), vascularized fibula (Capanna) (N = 7), and 3D printed customized titanium implants (N = 2), between the years 2016–2020. All patients were operated on with a 3D surgical workflow, including intraoperative PSIs, and were followed up postoperatively for at least 12 months (average 31.40 ± 12.13 months) to assess oncological and functional outcomes. ResultsAll patients demonstrated negative surgical margins, apart from one patient who had planned positive margins. Three patients suffered from short-term complications, and three patients underwent revision surgery due to graft non-union or pathological fracture. One patient suffered from local recurrence and underwent above-knee amputation. Three patients suffered from lung metastasis. MSTS at 12-month follow-up was 26.9.±5.87. ConclusionCustomized 3D-printed osteotomy PSIs provide surgeons with a novel tool for optimizing bone resection and reconstruction in long bones surgeries, thus minimizing overall tissue trauma and reducing the risk of damage to nervous and vascular structures. This study demonstrates that the use of PSIs has the potential to improve functional and oncological outcomes. We believe that this technique will become increasingly popular in the future as a widely applicable, highly accurate, cost-effective optimization tool.

“In-house” Design and Use of 3-dimensional Printed Patient-specific Bone Tumor Resection Guides for Geometric Osteotomies in Sarcoma Surgery

Three-dimensional printing technology has rapidly advanced as a promising technology for preoperative planning, education, and surgical execution in orthopedic surgery. Use of patient-specific instrumentation in orthopedic oncology sarcoma cases can streamline complex osteotomies while providing safe margins based on predetermined osteotomy levels. We describe use of an “in-house” protocol to create patient-specific bone tumor resection guides for use in orthopedic oncology cases. The described protocol bypasses expensive outsourcing options and facilitates use of preoperative surgical simulation and intimate involvement of the surgical team in the guide design. We report on the successful design and use of three-dimensional printed patient-specific bone tissue resection guides in a case of proximal tibial parosteal osteosarcoma resection and reconstruction with a size-matched allograft, and in a case of a secondary pelvic chondrosarcoma resection.

Three-Dimensional Patient Specific Instrumentation and Cutting Guide for Medial Closing Wedge High Tibial Osteotomy to Correct Valgus Malalignment

Achievement of appropriate mechanical knee alignment is crucial to ensure optimal clinical outcomes following osteotomy procedures about the knee. The use of patient-specific instrumentation (PSI) to assist in preoperative planning and intraoperative realignment has gained increasing popularity. The purpose of this article is to describe a surgical technique involving a medial closing wedge high tibial osteotomy performed using three-dimensional (3D) PSI and cutting guide to revise residual valgus deformity following failed distal femoral osteotomy. The correction angle, 3D position of the hinge and wedge, as well as final plate and screw position are planned preoperatively using virtual software and computed tomography imaging to allow precise surgical execution.

Early experience and patient-reported outcomes of 503 INFINITY total ankle arthroplasties.

This is a multicentre, non-inventor, prospective observational study of 503 INFINITY fixed bearing total ankle arthroplasties (TAAs). We report our early experience, complications, and radiological and functional outcomes. Patients were recruited from 11 specialist centres between June 2016 and November 2019. Demographic, radiological, and functional outcome data (Ankle Osteoarthritis Scale, Manchester Oxford Questionnaire, and EuroQol five-dimension five-level score) were collected preoperatively, at six months, one year, and two years. The Canadian Orthopaedic Foot and Ankle Society (COFAS) grading system was used to stratify deformity. Early and late complications and reoperations were recorded as adverse events. Radiographs were assessed for lucencies, cysts, and/or subsidence. In all, 500 patients reached six-month follow-up, 420 reached one-year follow-up, and 188 reached two-year follow-up. The mean age was 67.8 years (23.9 to 88.5). A total of 38 patients (7.5%) presented with inflammatory arthritis. A total of 101 (20.0%) of implantations used patient-specific instrumentation; 167 patients (33.1%) underwent an additional procedure at the time of surgery. A total of seven patients died of unrelated causes, two withdrew, and one was lost to follow-up. The mean follow-up was 16.2 months (6 to 36). There was a significant improvement from baseline across all functional outcome scores at six months, one, and two years. There was no significant difference in outcomes with the use of patient-specific instrumentation, type of arthritis, or COFAS type. Five (1.0%) implants were revised. The overall complication rate was 8.8%. The non-revision reoperation rate was 1.4%. The 30-day readmission rate was 1.2% and the one-year mortality 0.74%. The early experience and complications reported in this study support the current use of the INFINITY TAA as a safe and effective implant in the treatment of end-stage ankle arthritis. Cite this article: Bone Joint J2021;103-B(7):1270-1276.

New technologies (robotics, "custom-made") for unicondylar knee arthroplasty-contra

Numerous long-term results for both medial and lateral unicondylar knee arthroplasty (UKA) demonstrate that UKA is areliable and successful treatment for isolated anteromedial or lateral osteoarthritis of the knee when the correct indications are used. The relationship between operation volume and implant performance has clearly been established from recent studies and registry data. The use of novel technologies allows for an improvement in the accuracy of implant positioning with fewer outliers. However, evidence-based target zones for the positioning of available implants have not been sufficiently established. Current data does not support the routine use of patient-specific instruments or custom-made implants. Robot-assisted procedures must be interpreted as avery promising approach for the future. So far, there is insufficient evidence that robotically assisted surgical techniques improve implant performance or lead to better functional results from the patient's point of view.

Patient-specific cruciate-retaining total knee replacement with individualized implants and instruments (iTotal™ CR G2).

Treatment of tricompartimental osteoarthritis (OA) using customized instruments and implants for cruciate-retaining total knee arthroplasty. Use of patient-specific instruments and implants (ConforMIS iTotalTM CR G2) together with a 3D-planning protocol (iView®). Retropatellar resurfacing is optional. Symptomatic tricompartmental OA of the knee (Kellgren-Lawrence stageIV) with preserved posterior cruciate ligament (PCL) after unsuccessful conservative or joint-preserving surgical treatment. Knee ligament instabilities of the posterior cruciate or collateral ligaments. Infection. Relative contraindication: knee deformities >15° (varus, valgus, flexion); prior partial knee replacement. Midline or parapatellar medial skin incision, medial arthrotomy; distal femoral resection with patient-specific cutting block; tibial resection using either acutting jig for the anatomic slope or afixed 5° slope. Balancing the knee in extension and flexion gap using patient-specific spacer.The final tibial preparation achieved with gap-balanced placement of the femoral cutting jigs. Kinematic testing using anatomic trial components. Final implant components are cemented in extension. Wound layers are sutured. Drainage is optional. Sterile wound dressing; compressive bandage. No limitation of the active and passive range of motion. Optional partial weight bearing during the first 2weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52weeks, then every 1-2years. Overall 60patients with tricompartmental knee OA and preserved PCL were treated. Mean age was 66 (range 45-76) years. Minimum follow-up was 12months. There was 1septic revision after alow-grade infection, 1reoperation to replace the patellar due to patellar osteoarthritis and 3manipulations under anesthesia (MUAs) to increase range of motion. Radiographic analyses demonstrated an ideal implant fit with less than 2 mm subsidence or overhang. The WOMAC score improved from 154.8points preoperatively to 83.5points at 1 year and 59.3points at 2years postoperatively. The EuroQol-5D Score also improved from 11.1points preoperatively to 7.7points at 1year postoperatively.

The UK INFINITY Study - Early Experience and Complications of a Multicenter series of 504 Total Ankle Arthroplasties.

CategoryAnkle Arthritis; AnkleIntroduction/Purpose:This is the first report from the UK INFINITY study. This is a multicentre, non-inventor, prospective observational study of 504 INFINITY fixed bearing total ankle arthroplasties. We report our early experience, complications, radiographic and functional outcomes of this prosthesis.Methods:Patients were recruited from 11 specialist centres between June 2016 and November 2019. Demographic, radiographic, and functional outcome data (Ankle Osteoarthritis Scale, Manchester Oxford Questionnaire and Euroquol 5D-5L) were collected preoperatively, at 6 months (454 patients), 1 year (328 patients) and 2 years (104 patients). The average age was 67.8 (range 23.9 to 88.5) and average BMI 29.9 (18.9 to 48.0). The COFAS grading system was used to stratify deformity. There were 259 (51.4%) COFAS Type 1, 122 (24.2%) COFAS Type 2, 32 (6.3%) COFAS 3 and 87 (17.3%) COFAS type 4. 38 patients (7.54%) presented with inflammatory arthritis. 101 (20.0%) of implantations utilised patient specific instrumentation (Prophecy). 169 (33.5%) of patients underwent an additional procedure at the time of surgery. Early and late complications and reoperations were recorded as adverse events. Radiographs were assessed for lucencies, cysts and/or subsidence.Results:There was a significant (p<0.01) improvement across all functional outcome scores at 6 months, which was sustained at one and two years. There was no significant difference with the use of patient specific instrumentation. 167 (33.1%) underwent additional procedures at index surgery. At the latest follow up 3 implants (0.6%) have been revised. One patient at 6 weeks for deep infection, one patient at 6 months for subsidence and one patient at 18 months for loosening. There were an additional 13 reoperations (2.6%) at the latest follow up.Conclusion:The UK INFINITY study is the largest reported multicentre study of a Total Ankle Arthroplasty to date. This study has shown a low early revision rate and high functional outcomes of the INFINITY prosthesis.

Augmented reality for base plate component placement in reverse total shoulder arthroplasty: a feasibility study

BackgroundAccurate glenoid positioning in reverse total shoulder arthroplasty (RSA) is important to achieve satisfying functional outcome and prosthesis longevity. Optimal component placement can be challenging, especially in severe glenoid deformities. The use of patient-specific instruments (PSI) and 3D computer-assisted optical tracking navigation (NAV) are already established methods to improve surgical precision. Augmented reality technology (AR) promises similar results at low cost and ease of use. With AR, the planned component placement can be superimposed to the surgical situs and shown directly in the operating field using a head mounted display. We introduce a new navigation technique using AR via head mounted display for surgical navigation in this feasibility study, aiming to improve and enhance the surgical planning.Methods3D surface models of ten human scapulae were printed from computed tomography (CT) data of cadaver scapulae. Guidewire positioning of the central back of the glenoid baseplate was planned with a dedicated computer software. A hologram of the planned guidewire with dynamic navigation was then projected onto the 3D-created models of the cadaver shoulders. The registration of the plan to the anatomy was realized by digitizing the glenoid surface and the base of the coracoid with optical tracking using a fiducial marker. After navigated placement of the central guidewires, another CT imaging was recorded, and the 3D model was superimposed with the preoperative planning to analyze the deviation from the planned and executed central guides trajectory and entry point.ResultsThe mean deviation of the ten placed guidewires from the planned trajectory was 2.7° ± 1.3° (95% CI 1.9°; 3.6°). The mean deviation to the planned entry point of the ten placed guidewires measured 2.3 mm ± 1.1 mm (95% CI 1.5 mm; 3.1 mm).ConclusionAR may be a promising new technology for highly precise surgical execution of 3D preoperative planning in RSA.

CT-based patient-specific instrumentation for total knee arthroplasty in over 700 cases: single-use instruments are as accurate as standard instruments

PurposeEfforts in total knee arthroplasty are made to improve accuracy for a correct leg axis and reduce component malpositioning using patient-specific instruments. It was hypothesized that use of patient-specific instruments (vs. computer-navigated and conventional techniques) will reduce the number of outliers. Our second hypothesis was that single-use instrumentation will lead to the same accuracy compared to patient-specific instruments made of metal.Methods708 primary total knee arthroplasties between 2014 and 2018 using computer tomography (CT)-based patient-specific cutting block technique and a preoperative planning protocol were retrospectively reviewed. Preoperative data [hip–knee–angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), tibial slope, femoral component flexion] was compared to postoperative performed standard radiological follow-up X-rays. Differences of > 3° between measurements were defined as outliers.ResultsOverall 500 prostheses using standard instrumentation and 208 prostheses using single-use instruments were implanted. Preoperative HKA axes (− 1.2°; p < 0.001), femoral component flexion (Δ 0.8°, p < 0.001), LDFA (Δ − 1.5°, p < 0.001), MPTA (Δ − 0.5°, p < 0.001) and tibial posterior slopes (Δ 0.5°, p < 0.001), respectively, were different from postoperative axes. More outliers occurred using standard (vs. single-use) instruments (p < 0.001) regarding postoperative HKA (ranges of standard- vs. single-use: instruments: HKA 178.0°–180.5° vs. 178.0°–180.5°, femoral component flexion 0.0°–6.0° vs. 0.0°–4.5°, LDFA 90.0°–91.0° vs. 90.0°–90.0°, MPTA 90.0°–90.0° vs. 90.0°–90.0°, tibial posterior slope − 10° to 10° vs. − 1° to 10°). No differences were seen for other angles measured. Comparing both systems, total number of outliers was higher using standard (8%) vs. single-use instruments (4.3%).ConclusionThis study shows a high accuracy of CT-based patient-specific instrumentation concerning postoperative achieved knee angles and mechanical leg axes. Single-use instruments showed a similar accuracy.Level of evidenceIII.

Patient-specific instrumentation improved three-dimensional accuracy in total knee arthroplasty: a comparative radiographic analysis of 1257 total knee arthroplasties

BackgroundThe purpose of this study was to compare restoration of mechanical limb alignment and three-dimensional component-positioning between conventional and patient-specific instrumentation in total knee arthroplasty.MethodsRadiographic data of patients undergoing mobile-bearing total knee arthroplasty (n = 1257), using either conventional (n = 442) or patient-specific instrumentation (n = 812), were analyzed. To evaluate accuracy of axis restoration and 3D-component-positioning between conventional and patient-specific instrumentation, absolute deviations from the targeted neutral mechanical limb alignment and planned implant positions were determined. Measurements were performed on standardized coronal long-leg and sagittal knee radiographs. CT-scans were evaluated for accuracy of axial femoral implant rotation. Outliers were defined as deviations from the targeted neutral mechanical axis of > ± 3° or from the intraoperative component-positioning goals of > ± 2°. Deviations greater than ± 5° from set targets were considered to be severe outliers.ResultsDeviations from a neutral mechanical axis (conventional instrumentation: 2.3°± 1.7° vs. patient-specific instrumentation: 1.7°± 1.2°; p < 0.001) and numbers of outliers (conventional instrumentation: 25.8% vs. patient-specific instrumentation: 10.1%; p < 0.001) were significantly lower in the patient-specific instrumentation group. Significantly lower mean deviations and less outliers were detected regarding 3D-component-positioning in the patient-specific instrumentation compared to the conventional instrumentation group (all p < 0.05).ConclusionsPatient-specific instrumentation prevented from severe limb malalignment and component-positioning outliers (> ± 5° deviation). Use of patient-specific instrumentation proved to be superior to conventional instrumentation in achieving more accurate limb alignment and 3D-component positioning, particularly regarding femoral component rotation. Furthermore, the use of patient-specific instrumentation successfully prevented severe (> 5° deviation) outliers.

Intraoperative Assessment of the Axial Rotational Positioning of a Modern Ankle Arthroplasty Tibial Component Using Preoperative Patient-Specific Instrumentation Guidance.

The use of patient-specific instrumentation (PSI) in modern total ankle replacement (TAR) has augmented positioning of the tibial component, eliminating the need for complex jigs. Coronal and sagittal alignment are intuitive with this design and have been studied, but axial rotation has not. The purpose of this study was to assess the relationship between the planned preoperative axial rotation as set by the PSI guide and the rotation determined intraoperatively with non-PSI instrumentation. This was a prospective cohort study of 22 consecutive cases. The axial rotation angle between the medial gutter and the tibial implant position on the preoperative CT-scan based plan was extracted. At the time of surgery, the medial gutter alignment instrument from the non-PSI instrumentation was inserted and an intraoperative axial photograph obtained to record the angle between the medial gutter and the axial rotation guide pins set by the PSI instrumentation. The 2 measurements were compared and further statistical analysis included Pearson correlation and paired Student t test. The average axial rotation angle between the medial gutter and the implant on the PSI preoperative plan was 5.4 ± 2.9 degrees, whereas the intraoperative photograph from the medial gutter alignment instrument to the pin was 5.9 ±3.8 degrees. This demonstrated a Pearson correlation of R = 0.54 and a P value of .53. The average difference between the two was -0.46 (95% CI: -2.04, 1.10), meaning that components were either slightly externally rotated or that the fork was aimed internally. Based on this group, 50% (11/22) were within 2 degrees of the target and 77% (17/22) were within 4 degrees of the target. Patient-specific guides allowed for reproducible rotational tibial component implantation in modern TAR. Further work is needed to better understand the biomechanical effects of the rotational profile and consequences on survivorship. Level IV, case series.

3D planning and surgical navigation of clavicle osteosynthesis using adaptable patient-specific instruments

BackgroundPreoperative three-dimensional planning and intraoperative navigation by patient-specific instruments is a promising method for the exact correction of bone deformities. Nevertheless, disadvantages of current concepts are the missing options of adapting the surgical plan intraoperatively. By providing the surgeons with a controlled length adjustment through the patient-specific instruments, the application area can usefully be expanded in the treatment of clavicle osteosyntheses.MethodsIn three cases, preoperative three-dimensional surgical planning with the intraoperative use of patient-specific instruments was applied. The computer-assisted assessments of clavicle deformities, the preoperative plan, and the design of patient-specific instruments were created on the basis of computed tomography data. Reduction guides for restoring length and rotation according to the mirrored healthy contralateral side were enhanced with adaptable length adjustment functions. The screw thread of the reduction guides enabled temporary distraction of the clavicle fracture fragments and a controlled compression of the optionally used interposed bone block between clavicle fragments.ResultsNavigated clavicle osteosyntheses by enhanced patient-specific instruments was executed uneventful in all three cases. The surgeon was able to adapt clavicle length in a planned axis intraoperatively as clinically desired.ConclusionComputer-assisted planning of clavicle osteosynthesis and surgical navigation with additional adaptable patient-specific instruments can usefully expand the previous application areas. By using guided length adjustments, the fragments and optionally the graft can be compressed along a planned axis as desired to ensure optimal bone healing.Level of evidenceBasic science study, Surgical technique

L’arthroplastie totale de genou sous navigation conduit à un meilleur alignement postopératoire que la technique conventionnelle ou l’instrumentation personnalisée dans un centre chirurgical à volume modéré

BackgroundProcedure volume is an important determinant of total knee arthroplasty (TKA) outcomes. We aimed to determine whether computer navigation or patient-specific instrumentation (PSI) would improve postoperative alignment in a low-volume setting. HypothesisPSI for TKA achieves better limb and implant alignment compared to conventional TKA and to computer navigated TKA. Materials and methodsThis is a retrospective cohort study of 385 primary TKAs (Women=59%. Mean age=67 years. Mean BMI=30.1kg/m2) which were performed using conventional instrumentation (n=117; 30%), computer navigation (n=209; 54%), or patient-specific instrumentation (n=59; 15%) in a low-volume center (<50 TKAs/year). The risk of postoperative limb and implant mechanical alignment outliers in the coronal plane (>3° from neutral), average alignment and operation time were assessed. ResultsThe risk of postoperative mechanical alignment outliers (>3°) was reduced by 89% in the navigated group (4% outliers) compared to the conventional group (35%) (RR=0.11; p<0.0001). No significant improvement was observed in the PSI group (27%) (RR=0.91; p=0.772). The risk of postoperative femoral component coronal alignment outliers was reduced by 63% in the navigated group (11%) compared to the conventional group (31%) (RR=0.37; p=0.018). No significant reduction in outliers was observed in the PSI group (32%) (RR=1.08; p=0.816). There was a reduction in the risk of tibial component coronal malalignment of 66% in the navigated group (5%) compared to the conventional group (13%) (RR=0.33; p=0.070). There was a two-fold increase in the risk of tibial component alignment outliers in the PSI group (29%) (RR=1.94; p=0.110). DiscussionNavigated TKA improved postoperative alignment. No evidence of improved alignment was seen with patient-specific instrumentation. The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data. Type of studyRetrospective cohort study Level IV.