CT based PSI blocks for osteotomies around the knee provide accurate results when intraoperative imaging is used

Abstract Purpose Correction osteotomies around the knee are common methods for the treatment of varus or valgus malalignment of the lower extremity. In recent years, patient specific instrumentation (PSI) guides were introduced in order to enhance the accuracy of these procedures. The purpose of this study was to determine the accuracy of CT based PSI guides for correction osteotomies around the knee of low volume osteotomy surgeons and to evaluate if CT based PSI blocks deliver a high degree of accuracy without using intraoperative fluoroscopy. Methods Two study arms with CT based PSI cutting blocks for osteotomies around the knee were conducted. Part one: A retrospective analysis of 19 osteotomies was made in order to evaluate the accuracy in the hands of a low volume surgeon on long-leg radiographs. Part two: A cadaveric study with 8 knees was performed for the purpose of analyzing the accuracy without using intraoperative fluoroscopy on pre- and postoperative CT scans. Hip-Knee-Ankle angle (HKA), lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) were analyzed. The mean absolute delta (∂) between the planned and postoperative parameters were calculated. The accuracy of both study arms were compared. Results Part one: The mean MPTA ∂, LDFA ∂ and HKA ∂ was 0.9°, 1.9° and 1.5°, respectively. Part two: The mean MPTA ∂ and LDFA ∂ was 3.5° and 2.2°, respectively. The mean ∂ of MPTA is significantly different between clinical patients with fluoroscopic control and cadaveric specimens without fluoroscopic control (P < 0.001). All surgeries were performed without complications such as a hinge fracture. Conclusion The clinical use of PSI guides for osteotomies around the knee in the hands of low volume surgeons is a safe procedure. The PSI guides deliver a reliable accuracy under fluoroscopic control whereas their non-use of intraoperative fluoroscopy leads to a lack of accuracy. The use of fluoroscopic control during PSI guided correction osteotomies is highly recommended. Level of evidence IV – Retrospective and experimental Study

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Computed Tomography-Based Patient-Specific Instrumentation Loses Accuracy with Significant Varus Preoperative Misalignment

The Journal of Knee Surgery ◽

10.1055/s-0040-1716381 ◽

2020 ◽

Author(s):

Vicente Jesús León-Muñoz ◽

Mirian López-López ◽

Alonso José Lisón-Almagro ◽

Francisco Martínez-Martínez ◽

Fernando Santonja-Medina

Keyword(s):

Computed Tomography ◽

Deformity Correction ◽

Patient Specific ◽

Control Group ◽

X Rays ◽

Varus Alignment ◽

Patient Specific Instrumentation ◽

Conventional Instrumentation ◽

The Mean ◽

Valgus Alignment

AbstractPatient-specific instrumentation (PSI) has been introduced to simplify and make total knee arthroplasty (TKA) surgery more precise, effective, and efficient. We performed this study to determine whether the postoperative coronal alignment is related to preoperative deformity when computed tomography (CT)-based PSI is used for TKA surgery, and how the PSI approach compares with deformity correction obtained with conventional instrumentation. We analyzed pre-and post-operative full length standing hip-knee-ankle (HKA) X-rays of the lower limb in both groups using a convention > 180 degrees for valgus alignment and < 180 degrees for varus alignment. For the PSI group, the mean (± SD) pre-operative HKA angle was 172.09 degrees varus (± 6.69 degrees) with a maximum varus alignment of 21.5 degrees (HKA 158.5) and a maximum valgus alignment of 14.0 degrees. The mean post-operative HKA was 179.43 degrees varus (± 2.32 degrees) with a maximum varus alignment of seven degrees and a maximum valgus alignment of six degrees. There has been a weak correlation among the values of the pre- and postoperative HKA angle. The adjusted odds ratio (aOR) of postoperative alignment outside the range of 180 ± 3 degrees was significantly higher with a preoperative varus misalignment of 15 degrees or more (aOR: 4.18; 95% confidence interval: 1.35–12.96; p = 0.013). In the control group (conventional instrumentation), this loss of accuracy occurs with preoperative misalignment of 10 degrees. Preoperative misalignment below 15 degrees appears to present minimal influence on postoperative alignment when a CT-based PSI system is used. The CT-based PSI tends to lose accuracy with preoperative varus misalignment over 15 degrees.

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Comparison of Time and Cost Savings Using Different Cost Methodologies for Patient-Specific Instrumentation vs Standard Referencing in Total Ankle Arthroplasty

Foot & Ankle Orthopaedics ◽

10.1177/2473011419884278 ◽

2019 ◽

Vol 4 (4) ◽

pp. 247301141988427

Author(s):

Ian Savage-Elliott ◽

Victor J. Wu ◽

Isabella Wu ◽

John Timothy Heffernan ◽

Ramon Rodriguez

Keyword(s):

Intraclass Correlation ◽

Cost Savings ◽

Patient Specific ◽

Fixed Cost ◽

Level Of Evidence ◽

Tourniquet Time ◽

Radiographic Outcomes ◽

Patient Specific Instrumentation ◽

Implant Size ◽

The Cost

Background: Patient-specific 3-D printing cutting blocks (PSI) have been used instead of traditional intramedullary cutting guides. We hypothesized that PSI would lead to significantly decreased operating room (OR) time and significant cost savings to our institution with noninferior radiographic outcomes and no difference in expected vs actual implant size when compared with standard referencing (SR). Methods: Patients who had undergone total ankle replacements at our institution from 2013 through 2016 were included in the study. Associations between demographic variables and postoperative alignment in the SR vs PSI group were calculated using the Wilcoxon rank-sum test and the intraclass correlation coefficient. The cost of the operation was calculated using both an institutionally based fixed cost of OR time and using Time Driven Activity Based Cost (TDABC) accounting. A total of 43 patients were included in the study, 13 in the SR group and 30 in the PSI group. Results: Operative time (168 vs 137 minutes) and tourniquet time (123 vs 113 minutes) were significantly lower in the PSI vs the SR group. PSI predictions were accurate 100% of the time for tibial components and 83% of the time for talar components. Average costs of TAA using PSI were significantly reduced by $7597.00 when using traditional OR accounting, whereas PSI was $836.00 more expensive on average using TDABC accounting. Conclusion: Further research is needed to determine the cost-effectiveness of PSI vs SR in TAA; however, it does appear to save time intraoperatively. The long-term effect on clinical outcomes requires further study. Level of Evidence: Level III, case-control study.

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

The Bone & Joint Journal ◽

10.1302/0301-620x.103b7.bjj-2020-2058.r2 ◽

2021 ◽

Vol 103-B (7) ◽

pp. 1270-1276

Author(s):

David N. Townshend ◽

Andrew J. F. Bing ◽

Timothy M. Clough ◽

Ian T. Sharpe ◽

Andy Goldberg ◽

...

Keyword(s):

Functional Outcome ◽

Early Experience ◽

Outcome Data ◽

Patient Specific ◽

Patient Specific Instrumentation ◽

Significant Difference ◽

Patient Reported ◽

The Mean ◽

One Year

Aims 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. Methods 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. Results 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%. Conclusion 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 J 2021;103-B(7):1270–1276.

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Patient-Specific Instrumentation Combined With A New Tool for Gap Balancing Is Useful in Total Knee Replacement: 3-Year Follow-Up of A Retrospective Study

10.21203/rs.3.rs-129846/v1 ◽

2020 ◽

Author(s):

Ting Deng ◽

Tangyou Liu ◽

Qing Lei ◽

Lihong Cai ◽

Song Chen

Keyword(s):

Knee Function ◽

Patient Specific ◽

Gap Balancing ◽

Leg Axis ◽

Patient Specific Instrumentation ◽

Measured Resection ◽

Vas Scores ◽

Total Knee ◽

The Mean

Abstract Objective：The purpose of this study was to prove that knee function is well recovered using gap balancing technique with patient-specific instrumentation（PSI）combined a new balancer device in total knee arthroplasty (TKA) compared with the measured resection technique.Materials and methods：Data of 152 patients received TKA from August 2014 to June 2016 were studied retrospectively. Gap balancing technique assisted by PSI combined a new balance device was used in 80 patients (82 knees) and the measured resection technique was used in the surgery in 70 patients (70 knees). The data of surgery, imaging and knee function were compared. Results：The gap balancing technique assisted by PSI and a new balancer device was feasible in all operated knees and found to be reliable. In total, 152 patients (150 knees) with ages ranging from 52 to 78 years (mean 67 years) underwent TKA during the study period. The follow-up ranged from 35 to 52 months (mean 45 months). Only one patient underwent revision surgery in gap balance group at 2 years postoperatively due to infection. There was no difference in the incidence of anterior knee pain between the two groups. 2 patients received or required revisions. Until the latest follow-up, the mean flexion degree、KSS scores、VAS scores were not significantly different between the measured resection group and gap-balancing group at 12 weeks and 36 weeks. The average joint line displacement in GB group was 1.3 ± 1.1 mm (range 0-3) proximal and 1.2±1.4 mm in MR group. No outliers＞5 mm in each group were recorded. The mean leg axis was 1.8°±1.5°varus (range 0°-3°varus) versus the neutral mechanical axis in GB group and 1.4°±1.2°(range 0°-3°)in MR group. No outliers with＞ 3° deviation in each group were recorded.Conclusions：The gap balancing technique assisted by the new balancer device and PSI can be used to achieve accurate femoral component alignment as well as measured resection in 3 years outcomes. The new balancer device can be taken into account by surgeons who prefer the gap-balancing technique together with the PSI.

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The Relationships between the Rotational Axes of the Distal Femur in the Arthritic Caucasian Knee: A Magnetic Resonance Imaging Analysis

The Journal of Knee Surgery ◽

10.1055/s-0040-1709676 ◽

2020 ◽

Author(s):

Mansur Halai ◽

Sahil Kooner ◽

Bilal Jamal ◽

Jacquelyn McMillan ◽

Brian Syme ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

External Rotation ◽

Axial Rotation ◽

Secondary Outcome ◽

Patient Specific ◽

Resonance Imaging ◽

Coronal Alignment ◽

Patient Specific Instrumentation ◽

The Mean

AbstractFour distal femoral axes have been described to aid in the accuracy of transverse plane component alignment in total knee arthroplasty (TKA). These include the surgical epicondylar axis (SEA), the posterior condylar axis (PCA), and the anteroposterior (AP) axis. Therefore, the primary purpose of this study is to identify the axial femoral relationship with the least variation in a Caucasian population awaiting TKA for osteoarthritis. Secondarily, we further plan to determine if these femoral axis relationships differ with respect to sex or preoperative coronal alignment. These anatomic relationships were measured using preoperative magnetic resonance imaging, which was performed within 2 months of the planned operation date for patient specific instrumentation templating. In terms of our primary outcome, the mean SEA/AP angle was 92.8 degrees (standard deviation [SD]: 2.5 degrees), the mean PCA/AP angle was 95.7 degrees (SD: 2.8 degrees), and the mean PCA/SEA angle was 3.4 degrees (SD: 1.8 degrees). Overall, the PCA/SEA relationship had the smallest variance, while the PCA/AP had the most variance for all comparisons. In terms of our secondary outcome, there was no statistical difference between femoral axis relationships based on preoperative coronal plane alignment. In terms of sex differences, the PCA/SEA was significantly higher in female knees compared with males. Females had a PCA/SEA relationship of 4.7 degrees (SD: 1.3 degrees) compared with 2.6 degrees (SD: 1.2 degrees) for males (p < 0.05). By using the PCA/AP axes, the AP axis was externally rotated by 96.7 degrees (SD: 2.3 degrees) in females, compared with 93.2 degrees (SD: 2.1 degrees) in males, from the PCA. In conclusion, our results demonstrate that the PCA/SEA relationship should be used to determine axial rotation in TKA as it shows the least variation. When using the PCA, approximately 5 degrees of external rotation for Caucasian women and 3 degrees of external rotation for the Caucasian men should be dialed into the femoral cutting block to restore anatomic axial rotation. Further evaluation is needed to determine to role of preoperative coronal alignment on distal femoral axial alignment.

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Post Operative Analysis of a Novel Application of Surgical Navigation

10.29007/qmm6 ◽

2020 ◽

Author(s):

Benjamin Roberts ◽

Willy Theodore

Keyword(s):

Surgical Navigation ◽

Sagittal Alignment ◽

Low Cost ◽

Femoral Condyle ◽

Computer Assisted Surgery ◽

Patient Specific ◽

Computer Assisted ◽

Tibial Resection ◽

Patient Specific Instrumentation ◽

The Mean

A cohort of 84 patients underwent Total Knee Replacement surgery using Patient Specific Instrumentation fitted with an optical tracker that was monitored by a Computer Assisted Surgery system. The CAS system was low cost with small footprint in the operating theatre. The hip centre was collected and four other landmarks were recorded as rotational measures. The CAS system then reported the deviation in PSI placement against the targeted PSI placement, the surgeon then made a judgement whether to replace the guide. Post-operative analysis was done to determine the achieved alignment of the component and compared to the targeted alignment. From 45 results available for analysis the study found that the mean of rotational measures over the femur and tibia were found to be within ±30 of the targeted alignment, except for femur sagittal alignment. When a single outlier was removed from the femur sagittal alignment measures, the mean fell below ±30 of the targeted alignment. Distal femoral condyle resection measures fell below a mean of 1mm and posterior femoral condyle measures fell below a mean of 2mm. Lateral proximal tibial resection fell below a mean of 2.5mm as did medial proximal tibial resection when two outliers were removed. This shows that a CAS system incorporating the low cost, quicker time, and smaller footprint benefits of PSI with the accuracy of traditional navigation may be a feasible device.

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TRENDS IN UNICOMPARTMENTAL KNEE ARTHROPLASTY

Acta Ortopédica Brasileira ◽

10.1590/1413-785220202801222851 ◽

2020 ◽

Vol 28 (1) ◽

pp. 19-21 ◽

Cited By ~ 2

Author(s):

Ahmet Nadir Aydemir ◽

Mehmet Yucens

Keyword(s):

Knee Arthroplasty ◽

Unicompartmental Knee Arthroplasty ◽

Case Reports ◽

Research Articles ◽

Patient Specific ◽

Level Of Evidence ◽

Specific Level ◽

Unicompartmental Knee ◽

Patient Specific Instrumentation ◽

Thomson Reuters

ABSTRACT Objective: To evaluate trends in publications on unicompartmental knee arthroplasty (UKA) from the past to the present. Methods: As a web-based analysis, all UKA research articles, editorial letters, case reports, reviews and meeting abstracts published on the Thomson Reuters’ Web of Knowledge were evaluated. The period from the first publication in 1980 to January 2019 was divided into four decades and publications were evaluated. Research articles were grouped into headings according to the subjects. Results: A total of 1,658 publications were evaluated in this study. The most frequent term used in the publications title was “outcome,” with 260 items, followed by “biomechanics and kinematics,” with 99 items. Most reports have been published in the last decade, and the most common type of publication was postoperative follow-up and results. Conclusion: In parallel with technological advancements, publications related to UKA-especially patient-specific instrumentation, navigation, and robotic surgery-will increase in number and become more specific. Level of Evidence V, Expert Opinion.

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Release of partial syndactyly using a trident flap without skin grafting

Journal of Hand Surgery (European Volume) ◽

10.1177/1753193419882900 ◽

2019 ◽

Vol 45 (2) ◽

pp. 181-186

Author(s):

Stéphane Guero

Keyword(s):

Analogue Scale ◽

Skin Grafting ◽

Safe Procedure ◽

Flap Necrosis ◽

Level Of Evidence ◽

Single Operator ◽

Cosmetic Outcomes ◽

The Mean ◽

Quantitative Scoring

We reviewed outcomes of a modified trident flap technique in 83 patients for a series of partial syndactyly releases performed by a single operator over 30 years. Only patients with at least 3 years of follow-up (range 3 to 27 years) were included. One-hundred and twenty-seven procedures were performed for 83 patients, and no cases of flap necrosis occurred. Three hands had Grade 1 web creep on Withey’s semi-quantitative scoring system, and two had Grade 2 web creep. Revision surgery was required for one minor contracture and one intermediate contracture. Abduction angles of up to 30° were measured for operated adjacent fingers. The mean satisfaction score of the child or parents on the visual analogue scale was 1.1. The trident flap is a safe procedure, with excellent functional and cosmetic outcomes. The residual scarring is limited to the web, and there is no scarring on the dorsum of the hand. Level of evidence: IV

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

Foot & Ankle International ◽

10.1177/1071100719856548 ◽

2019 ◽

Vol 40 (10) ◽

pp. 1160-1165

Author(s):

Oliver J. Gagne ◽

Andrea Veljkovic ◽

Dave Townshend ◽

Alastair Younger ◽

Kevin J. Wing ◽

...

Keyword(s):

Tibial Component ◽

Rotation Angle ◽

Pearson Correlation ◽

Case Series ◽

Axial Rotation ◽

Patient Specific ◽

P Value ◽

Level Of Evidence ◽

Patient Specific Instrumentation ◽

Preoperative Ct

Background: 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. Methods: 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. Results: 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. Conclusion: 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 of Evidence: Level IV, case series.

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