Patient-specific Cutting Guides Research Articles

Patient-specific cutting guides in corrective osteotomy near to the knee joint

Patient-specific cutting guides (PSCG) are used in osteotomy near to the knee joint to simplify the operative technique, shorten the duration of surgery, reduce radiation exposure and to exactly realize the preoperative planning during surgery, especially when complex deformities are corrected simultaneously in multiple planes. The application of PSCG is in principle possible in all osteotomies near to the knee joint but is especially useful in multidimensional, complex osteotomy. No specific contraindications. After multidimensional 3D analysis and planning using apreoperative computed tomography (CT) protocol, a3D-printed patient-specific cutting guide is produced. This PSCG is used during standard osteotomy near to the knee. Using this PSCG the guided sawcut and predrilling of the screw positions inside the bone for the screws of the planned angle stable osteotomy plate are performed. The amount of the deformity correction needed is "stored" in the PSCG and is converted to the bony geometry during placement of the screws in the predrilled holes through the plate after opening or closing the osteotomy. Apart from that, the surgical approach and technique are equivalent to the standard osteotomy types near to the knee. The application of PSCG in osteotomy near to the knee does not change the postoperative management of the specific osteotomy. The use of patient-specific cutting guides leads to a higher accuracy in the implementation of the preoperative planning and the desired target axis is achieved with greater accuracy. Multidimensional complex corrections can also be exactly planned and implemented. In addition, the intraoperative radiation exposure for the operation team can possibly be reduced.

Double-level knee osteotomy accurately corrects lower limb deformity and provides satisfactory functional outcomes in bifocal (femur and tibia) valgus malaligned knees.

Double-level knee osteotomy (DLO) is a challenging procedure that requires precision in preoperative planning and intraoperative execution to achieve the desired correction. It is indicated in cases of severe varus or valgus deformities where a single-level osteotomy would yield significantly tilted joint line obliquity (JLO). This study aimed to evaluate the effectiveness of DLO in achieving accurate correction without compromising JLO, using patient-specific cutting guides (PSCGs), in cases of bifocal valgus maligned knees. A single-centre, retrospective analysis of prospectively collected data for a total of 26 patients, who underwent DLO by PSCGs for valgus malaligned knees, between 2015 and 2020. Post-operative alignment was evaluated and the delta for different lower limb0.05, not statistically significant (ns)). All KOOS subs alignment parameters was calculated; the hip-knee-ankle angle (ΔHKA), medial proximal tibial angle (ΔMPTA), and lateral distal femoral angle (ΔLDFA). At the two-year follow-up, changes in the KOOS sub-scores, UCLA scores, lower limb discrepancy (LLD), and mean time to return to work and sport were recorded. All intraoperative and postoperative complications were recorded. The Mann-Whitney U test with a 95% confidence interval (95% CI) was used to evaluate the differences between two variables; one-way ANOVA between more than two variables and the paired Student's t-test was used to estimate the evolution of functional outcomes. The postoperative mean ΔHKA was 0.9 ± 0.9°, the mean ΔMPTA was 0.7 ± 0.7°, and the mean ΔLDFA was 0.7 ± 0.8° (all values with p > 0.05, not statistically significant (ns)). All KOOS subscore's mean values were improved to an extent two-fold superior to the reported minimal clinically important difference (MCID) (all with p < 0.0001). There was a significant increase in the UCLA score at the final follow-up (5.4 ± 1.5 preoperatively versus 7.7 ± 1.4, p < 0.01). The mean time to return to sport and work was 4.7 ± 1.1 and 4.3 ± 2.1months, respectively. There was an improvement in Lower-limb discrepancy preoperative (LLD = 1.3 ± 2cm) to postoperative measures (LLD = 0.3 ± 0.4cm), ns. Complications were 2 femoral hinge fractures, 2 deep vein thromboses, 1 delayed tibial healing, and 1 hardware removal for hamstring irritation syndrome. DLO is effective and safe in achieving accurate correction in bifocal valgus malaligned knees with maintained lower limb length and low complication rate with no compromise of JLO. III.

Are Patient Specific Cutting Guides Better Alternative to Conventional Instrumentation in Primary Total Knee Arthroplasty? “-Prospective Randomized Comparative Study

Arthroscopy and Arthroplasty fellow, Sant Parmanand Hospital and Delhi Institute of Trauma and Orthopedics New Delhi, India

Time is Money! Influence on Operating Theater and Sterilization Times of Patient-specific Cutting Guides and Single-use Instrumentation for Total Knee Arthroplasty: A Full Factorial Design of 136 Patients.

BackgroundPatient-specific cutting guides (PSGs) and single-use disposable instrumentation (SUI) have emerged as potential beneficial innovations for total knee arthroplasty. The aim of this study was to evaluate the impact of PSG and SUI for total knee arthroplasty on operating room (OR) and sterilization times.MethodsA monocentric, prospective, interventional, full factorial design study, including 136 patients, compared patient-specific (PSG, n = 68) to conventional cutting guides (n = 68) and SUI (n = 68) to conventional instrumentation (CVI, n = 68). In the OR, we recorded the number of instrument trays, operating time, and room occupancy time. In the central sterile services department, the total sterilization duration was assessed. The primary outcome was operating time and sterilization duration. Secondary outcomes were difference in the number of trays, Oxford Knee Score, and postoperative mechanical axis.ResultsThe median operating time was 80 minutes (Q1-Q3: 73-90) and was significantly increased for SUI compared to that for CVI (+5 minutes, P = .0072). The median sterilization duration was 1261 minutes (Q1-Q3: 934-1603). It was significantly in favor of SUI (936 minutes) over CVI (1565 minutes) (+629 minutes, P < .0001). The total number of instrument trays was 404 for 136 patients: 252 for CVI and 152 for SUI (P < .0001) and 189 for PSG and 215 for conventional cutting guides (P = .0006). There was no significant difference in OKS (P = .86) nor in the postoperative alignment which was between 177° and 183° (75% patients, P = .24).ConclusionsSUI lowers the number of instrument trays and sterilization duration. PSG is not associated with significant OR or sterilization time reduction. The use of SUI could reduce the risk of noncompliance of instrument trays.

Patient specific instrumentation allow precise derotational correction of femoral and tibial torsional deformities

BackgroundRotational malalignment deformities of the lower limb in adults mostly arise from excessive femoral anteversion and/or excessive external tibial torsion. The aim of this study was to assess the correction accuracy of a patient specific cutting guides (PSCG) used in tibial and femoral correction for lower-limb torsional deformities. MethodsForty knees (32 patients) were included prospectively. All patients had patellofemoral pain or instability with torsional malalignment for which a proximal tibial (HTO) or distal femoral (DFO) or a double-level osteotomy (DLO) had been performed. Accuracy of the correction between the planned and the postoperative angular values including femoral anteversion, tibial torsion, coronal and sagittal alignment were assessed after tibial and/or femoral osteotomy. ResultsForty knees were included in this study. In cases of HTO, the correction accuracy obtained with PSCG was 1.3 ± 1.1° for tibial torsion (axial plane), 0.8 ± 0.7° for MPTA (coronal plane) and 0.8 ± 0.6° for PPTA (sagittal plane). In cases of DFO, the correction accuracy obtained with PSCG was 1.5 ± 1.4° for femoral anteversion (axial plane), 0.9 ± 0.9° for LDFA (coronal plane) and 0.9 ± 0.9° for PDFA (sagittal plane). The IKSG was improved from 58.0 ± 13.2° to 71.4 ± 10.9 (p = 0.04) and the IKSF from 50.2 ± 14.3 to 87.0 ± 6.9 (p < 0.001). ConclusionsUsing the PSCG for derotational osteotomy allows excellent correction accuracy in all the three planes for femoral and tibial torsional deformities associated with patellofemoral instability.Level of clinical evidence II, prospective cohort study.

Double level knee osteotomy using patient-specific cutting guides is accurate and provides satisfactory clinical results: a prospective analysis of a cohort of twenty-two continuous patients.

Double level osteotomy (DLO) (femoral and tibial) is a technically demanding procedure for which pre-operative planning accuracy and intraoperative correction are key factors. The aim of this study was to assess the accuracy of the achieved correction using patient-specific cutting guides (PSCGs) compared to the planned correction, its ability to maintain joint line obliquity (JLO), and to evaluate clinical outcomes and level of patient satisfaction at a follow-up of twoyears. A single-centre, prospective observational study including 22 patients who underwent DLO by PSCGs between 2014 and 2018 was performed. Post-operative alignment was evaluated and compared with the target angular values to define the accuracy of the correction for the hip-knee-ankle angle (ΔHKA), medial proximal tibial angle (ΔMPTA), lateral distal femoral angle (ΔLDFA), and posterior proximal tibial angle (ΔPPTA). Pre- and post-operative JLO was also evaluated. At twoyear follow-up, changes in the KOOS sub-scores and patient satisfaction were recorded. The Mann-Whitney U test with 95% confidence interval (95% CI) was used to evaluate the differences between two variables; the paired Student's t test was used to estimate evolution of functional outcomes. The mean ΔHKA was 1.3 ± 0.5°; the mean ΔMPTA was 0.98 ± 0.3°; the mean ΔLDFA was 0.94 ± 0.2°; ΔPPTA was 0.45 ± 0.4°. The orientation of the joint line was preserved with a mean difference in the JLO of 0.4 ± 0.2. At last follow-up, it was recorded a significant improvement in all KOOS scores, and 19 patients were enthusiastic, two satisfied, and one moderately satisfied. Performing a DLO using PSCGs produces an accurate correction, without modification of the joint line orientation and with good functional outcomes at twoyear follow-up.

Patellar height is not modified after isolated open-wedge high tibial osteotomy without change in posterior tibial slope

IntroductionOpen-wedge high tibial osteotomy (OWHTO) corrects coronal deformity and can impact sagittal parameters such as posterior tibial slope and patellar height. The aim of the present study was to analyze change in patellar height after medial OWHTO with respect to tibial and femoral-referenced indices. Material and methodThis single-center retrospective study included 129 patients undergoing isolated posteromedial OWHTO, without change in tibial slope, using patient-specific cutting-guides. Patellar height was assessed on Caton-Deschamps (CD), Insall-Salvati (IS) and Schröter indices. Posterior tibial slope and coronal femoral and tibial angles were also measured. X-rays were taken preoperatively and at 12 months, and analyzed by 2 independent observers. ResultsOWHTO modified the global lower-limb alignment (Δ=6.3±0.95̊, p<0.0001) and the proximal tibial deformity (Δ=7±0.88̊, p<0.0001). Posterior tibial slope and tibial (CD and IS) and femoral (Schröter) patellar height indices were unchanged. Intra- and inter-observer reproducibility was excellent (ICC 0.79–0.91). There were no correlations between HKA or MPTA angles and change in patellar height. ConclusionThe present clinical series showed that patellar height was unchanged by isolated posteromedial OWHTO without change in tibial slope, using patient-specific cutting-guides, with whichever femoral or tibial reference index. The Schröter patellar femoral height index was highly reliable and is independent of proximal tibial changes in assessing patellar height, and can thus be recommended in the follow-up of OWHTO. Level of evidenceIII; retrospective cohort study.

Evaluation of the "Minimal Clinically Important Difference" (MCID) of the KOOS, KSS and SF-12 scores after open-wedge high tibial osteotomy.

Defining a Minimal Clinically Important Difference (MCID) value for Patient-Reported Outcome Measures (PROMs) is crucial for determining the effectiveness of a procedure and calculating the sample size for trial planning. The purpose of this study was to determine the MCID of several PROMs (Knee injury and Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS) and the SF-12) in patients who underwent medial opening-wedge High-Tibial Osteotomy (owHTO) with Patient-Specific Cutting Guides (PSCGs), using anchor-based methods. Patients undergoing isolated medial owHTO with PSCGs between January 2013 and January 2017 were enrolled in this single-center, prospective, observational study. Three outcome scores were collected pre-operatively and at the 2 years follow-up evaluation: KOOS, KSS and SF-12. The MCIDs were calculated using anchor-based method: at 2 years postoperatively: "Compared with before surgery, how would you rate operated joint now?" The responses were recorded using a five-point scale. Patients who answered "about the same" or "somewhat worse" were classified into the no change group, while those who answered "somewhat better" were classified into the minimal change group. A receiver operating characteristic (ROC) curve was used to define the cutoff point that best discriminated between the minimal change and no change groups for each PROMs RESULTS: 196 patients were included, 75 (somewhat better) and 24 patients (about the same and somewhat worse) were, respectively, assigned to the "no change" and "minimal change" groups. There was no significant difference between the two groups in terms of baseline characteristics and postoperative complications. At 24months follow-up all the PROMs (KOOS, KSS and SF-12) were significantly better for the "minimal change" group compared to the "no change" group. MCID was 15.4 for KOOS pain, 15.1 for KOOS symptoms, 17 for KOOS ADL, 11.2 for KOOS sports/recreation, 16.5 for KOOS QQL, 3 for KSS symptoms, 5.6 for KSS activity, 7.2 for SF-12 physical component and 6.3 for PCS mental component. This study determined the MCIDs of common used PROMs in patients undergoing owHTO. Prospective Cohort Study, Level II.

Patient-specific high-tibial osteotomy's 'cutting-guides' decrease operating time and the number of fluoroscopic images taken after a Brief Learning Curve.

Patient-specific cutting guides (PSCGs) have been advocated to improve the accuracy of deformity correction in opening-wedge high-tibial osteotomies (HTO). It was hypothesized that PSCGs for HTO would have a short learning curve. Therefore, the goals of this study were to determine the surgeons learning curve for PSCGs used for opening-wedge HTO assessing: the operating time, surgeons comfort levels, number of fluoroscopic images, accuracy of post-operative limb alignment and functional outcomes. This prospective cohort study included 71 consecutive opening-wedge HTO with PSCGs performed by three different surgeons with different experiences. The operating time, the surgeon's anxiety levels evaluated using the Spielberger State-Trait Anxiety Inventory (STAI), the number of fluoroscopic images was systematically and prospectively collected. The accuracy of the postoperative alignment was defined by the difference between the preoperative targeted correction and the final post-operative correction both measured on standardized CT-scans using the same protocol (ΔHKA, ΔMPTA, ΔPPTA). Functional outcomes were evaluated at 1 year using the different sub-scores of the KOOS. Cumulative summation (CUSUM) analyses were used to assess learning curves. The use of PSCGs in HTO surgery was associated with a learning curve of 10 cases to optimize operative time (mean operative time 26.3min ± 8.8), 8 cases to lessen surgeon anxiety levels, and 9 cases to decrease the number of fluoroscopic images to an average of 4.3 ± 1.2. Cumulative PSCGs experience did not affect accuracy of post-operative limb alignment with a mean: ΔHKA = 1.0° ± 1.0°, ΔMPTA = 0.5° ± 0.6° and ΔPPTA = 0.4° ± 0.8°. No significant difference was observed between the three surgeons for these three parameters. There was no statistical correlation between the number of procedures performed and the patient's functional outcomes. The use of PSCGs requires a short learning curve to optimize operating time, reduce the use of fluoroscopy and lessen surgeon's anxiety levels. Additionally, this learning phase does not affect the accuracy of the postoperative correction and the functional results at 1year. II: prospective observational study.

Patient-specific cutting guides for open-wedge high tibial osteotomy: safety and accuracy analysis of a hundred patients continuous cohort.

Several recent studies have reported accurate and reliable use of patient-specific cutting guides (PSCG) for medial opening-wedge high tibial osteotomy (OW-HTO); however, a majority of these are small cases series or ex-vivo reports. The hypothesis of this study was that performing an OW-HTO with PSCG results in a reliable and accurate correction with good or satisfactory patient-reported functional outcomes at a mean of twoyears. We also hypothesized that the use of PSCG would not increase the rate of specific or non-specific complications. In this single-centre, observational study, a prospective cohort of a hundred patients (age < 60years with isolated medial knee osteoarthritis and significant metaphyseal tibial vara) were included between February 2014 and November 2017 to investigate the safety and accuracy of OW-HTO using PSCG. The accuracy of post-operative alignment was defined by the difference between the desired correction defined pre-operatively and the correction obtained post-operatively measured on CT scan (ΔHKA, ΔMPTA, ΔPPTA). Functional outcomes were evaluated by the difference between the value obtained in the pre-operative questionnaire and that obtained at the last follow-up (mean 2years) using the KOOS and UCLA activity scale. Intra-operative and post-operative complications were recorded. The mean patient age was 44.17 ± 6.77years; no patient was lost to follow-up at a mean of twoyears. The mean ΔHKA was 1 ± 0.95°, the mean ΔMPTA was 0.54 ± 0.63°, and the mean ΔPPTA was 0.43 ± 0.8°. No significant differences (all p values > 0.05) were observed between the desired correction defined pre-operatively and the correction obtained post-operatively (ΔHKA, ΔMPTA, ΔPPTA). An improvement of 27 ± 25 for the KOOS Pain, 28 ± 26 for the KOOS symptoms, 27 ± 28 for the KOOS ADL, 26 ± 33 for the KOOS sport/rec, 28 ± 38 for the KOOS QOL, and 2.6 ± 2.4 for the UCLA was obtained as compared withthe pre-operative values (all p < 0.0001). No procedures observed were abandoned, and the PSCG was well positioned in all cases. The overall complication rate was 32% up to twoyears post-operatively, most of them being classed as minor events (28%). Performing an OW-HTO with PSCG produces an accurate correction with good functional outcomes at a mean of twoyears. Furthermore, there is no increase in the rate of specific or non-specific complications. A study to assess the reproducibility of this technique, regardless of the surgical level, is needed.

Second Generation Patient Specific Total Knees Demonstrate a Higher Manipulation Rate Compared with “Off-the-shelf” Implants

Introduction. Patient specific total knee arthroplasty (TKA) theoreticallyprovides a more accurate fit to the native knee but mayhave difficulty achieving full range of motion (ROM) post-operatively.Post-operative ROM data were compared between patientswho underwent cemented patient-specific cruciate-retaining(PSCR) and standard cemented posterior-stabilized (SPS) TKAs.&#x0D; Methods. PSCR and SPS TKAs that were performed from January2014 to September 2015 by the same surgeon using the same postoperativeprotocols at two selected facilities were reviewed. Twoandsix-week post-operative ROM data were obtained and thenumber of patients with knee flexion less than 110° was recorded.&#x0D; Results. Twenty-one patients in the PSCR group and 57 patientsin the SPS group were included. The percentage of patientswith knee flexion less than 110° was similar in both groups preoperatively(10% vs 14%, p = 0.60) and two-week post-operatively(57% vs 68%, p = 0.35). However, at six-week post-operativelythere was significant difference (29% vs 7%, p = 0.01).&#x0D; Conclusions. These results provide evidence to alert orthopaedicsurgeons when using these patient specific implants versus conventionalTKA methods. Patients whose TKA was performed usingpatient specific cutting guides struggled to obtain 110° of kneeflexion. Close monitoring, aggressive physical therapy, and earlymanipulation are recommended when using patient specific cuttingguides and custom total knee implants. Further evaluation ina larger group of patients is warranted. KS J Med 2016;9(4):88-92.

Can a Single-Use and Patient-Specific Instrumentation Be Reliably Used in Primary Total Knee Arthroplasty? A Multicenter Controlled Study

BackgroundThe aim of this controlled multicenter study is to evaluate the clinical and radiologic outcomes of primary total knee arthroplasty (TKA) using single-use fully disposable and patient-specific cutting guides (SU) and compare the results to those obtained with traditional patient-specific cutting guides (PSI) vs conventional instrumentation (CI). MethodsSeventy consecutive patients had their TKA performed using SU. They were compared to 140 historical patients requiring TKA that were randomized to have the procedure performed using PSI vs CI. The primary measure outcome was mechanical axis as measured on a standing long-leg radiograph using the hip-knee-ankle angle. Secondary outcome measures were Knee Society and Oxford knee scores, operative time, need for postoperative transfusion, and length of hospital stay. ResultsThe mean hip-knee-ankle value was 179.8° (standard deviation [SD] 3.1°), 179.2° (SD 2.9°), and 178.3° (SD 2.5°) in the CI, PSI and SU groups, respectively (P = .0082). Outliers were identified in 16 of 65 (24.6%), 15 of 67 (22.4%), and 14 of 70 (20.0%) knees in the CI, PSI, and SU group, respectively (P = .81). There was no significant difference in the clinical results (P = .29 and .19, respectively). Operative time, number of unit transfusion, and length of hospital stay were not significantly different between the 3 groups (P = .45, .31, and 0.98, respectively). ConclusionThe use of an SU in TKA provided similar clinical and radiologic results to those obtained with traditional PSI and CI. The potential economic advantages of single-use instrumentation in primary TKA require further investigation.

Can three-dimensional patient-specific cutting guides be used to achieve optimal correction for high tibial osteotomy? Pilot study

IntroductionTreatment of medial tibiofemoral osteoarthritis with a high-tibial osteotomy (HTO) is most effective when the optimal angular correction is achieved. However, conventional instrumentation is limited when multiplanar correction is needed. HypothesisUse of patient-specific cutting guides (PSCGs) for HTO provides an accurate correction (difference<2°) relative to the preoperative planning. Materials and methodsBetween February 2014 and February 2015, 10 patients (mean age: 46 years [range: 31–59]; grade 1 or 2 osteoarthritis in Ahlbäck's classification) were included prospectively in this reliability and safety study. All patients were operated using the same medial opening-wedge osteotomy technique. Preoperative planning was based on long-leg radiographs and CT scans with 3D reconstruction. The PSGCs were used to align the osteotomy cut and position the screw holes for the plate. The desired correction was achieved in the three planes when the holes on the plate were aligned with the holes drilled based on the PSCG. Preoperatively, the mean HKA angle was 171.9° (range: 166–179°), the mean proximal tibial angle was 87° (86–88°) and the mean tibial slope was 7.8° (1–22°). The postoperative correction was compared to the planned correction using 3D CT scan transformations. Intraoperative and postoperative complications were assessed at a minimum follow-up of 1 year. ResultsThe procedure was successfully carried out in all patients with the PSCGs. On postoperative long-leg radiographs, the mean HKA was 182.3° (180–185°); on the CT scan, the mean tibial mechanical angle was 94° (90–98°) and the mean tibial slope was 7.1° (4–11°). In 19 out of 20 postoperative HKA and slope measurements, the difference between the planned and achieved correction was <2° based on the 3D analysis of the three planes in space; in the other case, the slope was 13° instead of the planned 10°. The intra-class correlation coefficients between the postoperative and planned parameters were 0.98 [0.92–0.99] for the HKA and 0.96 [0.79–0.99] for the tibial slope. There were no surgical site infections; one patient had a postoperative hematoma that resolved spontaneously. DiscussionThe results of this study showed that use of PSCGs in HTO procedures helps to achieve optimal correction in a safe and reliable manner. Level of evidenceIV – Prospective cohort study.

Intra-Operative Experience using Magnetic Resonance Imaging (MRI) Based Patient Specific Cutting Guides during Total Knee Arthroplasty

Background. The incidence of malalignment in total knee arthroplasty(TKA) using conventional instrument has beenreported as high as 25%. A relatively new TKA system involvesthe use of a preoperative magnetic resonance image(MRI) to obtain accurate implant placement more consistently.For broad acceptance of this new technique, it iscrucial to analyze the initial intra-operative experience. Thespecific aim of this study was to evaluate the initial intra-operativeexperience of a single surgeon using this new technique.&#x0D; Methods. A total of 15 knees (12 patients: 6 female and 6male) were reviewed from TKA procedures using the selectedmanufacturer’s patient specific cutting guides between January2011 and April 2013 at a single institution. Patient demographicand specific parameters and intra-operative alterationsof component positioning were recorded and evaluated.Results. The preoperative plan was able to predict correctly thesize of the implanted femoral component in 87% (n = 13) andtibial component in 80% (n = 12) of the cases. However, 60% (n= 9) of cases required additional intra-operative corrections onfemoral resection, and 73% (n = 11) required an additional 2 - 4mm correction on the tibial proximal resection. Twenty percent(n = 3) required additional tibial varus/valgus correction, butthere were no tibial slope corrections for any of the 15 cases.&#x0D; Conclusions. The initial intra-operative experience of a singlesurgeon using current patient specific cutting guides for a selectedmanufacturer to align femoral and tibial components duringTKA has raised some concerns. We agreed with previous studiesthat caution should be taken when using patient specific cuttingguides without supportive data. The findings of this study providedadditional evidence to contest the accuracy of patient specificcutting guides with respect to the initial experience of an orthopaedicsurgeon who is trained in total joint replacement. Theresults provided more evidence to assist orthopaedic surgeonsin the decision of whether to use these patient specific systemsversus conventional TKA methods. KS J Med 2016;9(2):22-26.

Handheld Navigation Device and Patient-Specific Cutting Guides Result in Similar Coronal Alignment for Primary Total Knee Arthroplasty: a Retrospective Matched Cohort Study.

Proper alignment of total knee arthroplasty (TKA) is essential for TKA function and may reduce the risk of aseptic failure. Technologies that prevent malalignment may reduce the risk of revision surgery. The purpose of this study was to compare two competing TKA systems that purport improved alignment: patient-specific instrumentation (PSI), and a handheld portable navigation device (NAV). After IRB approval, 49 consecutive PSI TKAs (40 patients) were matched based on preoperative characteristics to 49 NAV TKAs (40 patients) performed by a single surgeon. A blinded observer measured alignment on digital radiographs. Operating room records were reviewed for procedure times. Two-tailed paired sample t tests and McNemar's test were used as appropriate. Alpha level was 0.05 for all tests. Preoperative cohort characteristics were not different. Mean postoperative long-leg mechanical alignment was within ±1° of neutral for both groups, although statistically different (p = 0.026). There were no other significant differences in coronal alignment. PSI exhibited significantly greater posterior tibial slope (4.4°) compared to NAV (2.7°) (p = 0.004); PSI resulted in significantly more outliers (>6°; p = 0.004). Procedure time for unilateral TKAs was lower for PSI (74.4min) compared to that for NAV (80.6min; p = 0.023). NAV and PSI technologies provided excellent coronal plane alignment. NAV was better for sagittal tibial slope, while PSI procedure times were shorter for unilateral TKA. The impact of these technologies on patient-reported outcomes and TKA survivorship is controversial and should be the focus of future research.

Patient-Specific Cutting Guides Were Not Better Than Conventional Instrumentation for Total Knee Arthroplasty.

Abane L, Anract P, Boisgard S, Descamps S, Courpied JP, Hamadouche M. A comparison of patient-specific and conventional instrumentation for total knee arthroplasty: a multicentre randomised controlled trial. Bone Joint J. 2015 Jan;97-B(1):56-63. ### Question: In patients having total knee arthroplasty, are better results achieved using patient-specific cutting guides (PSCG) compared with conventional instrumentation? ### Design: Randomized (allocation concealed), blinded (outcome assessor), controlled trial with 3 months of follow-up. ### Setting: 2 tertiary care centers in France. ### Patients: 140 patients between 18 and 85 years of age (mean age, 69 years; 63% women) with 140 knees requiring total knee arthroplasty because of primary or secondary osteoarthritis were enrolled. Exclusion criteria were active or suspected infection, tumor around the knee, previous total knee arthroplasty, the presence of hardware that could cause artifacts on magnetic resonance imaging (MRI), contraindication to MRI, the presence of deformity that required osteotomy around the knee or total knee arthroplasty, or social circumstances that could impair follow-up. 126 patients (90%) completed follow-up. ### Intervention: Patients were allocated to PSCG (n = 70) or conventional instrumentation (n = 70). Patients in the PSCG group were evaluated with MRI and standing full-length radiographs six weeks before surgery. A preliminary surgical plan, including the level of resection and the alignment and size of the femoral and tibial components, was formulated from the images according to the preference …

Contribution of patient-specific cutting guides to lower limb alignment for total knee arthroplasty

Patient-specific cutting guides (PSCG) are an extension of preoperative planning for total knee arthroplasty (TKA). We wanted to evaluate their contribution to postoperative lower limb alignment. This study involved primary TKA cases being performed with PSCG between 10/05/2010 and 05/03/2013 and then followed prospectively. The analysis involved the PSCG usage and postoperative measurement of the patient's HKA, medial distal femoral joint angle (MDFA) and medial proximal tibia joint angle (MPTA). Of the 104 eligible cases, 68 were included; 11 of these cases were not performed completely with the PSCG as initially planned. Thus we compared these 11 cases with the 57 where PSCG were used. The preoperative HKA in the included cases was 175.8°±7.8; the postoperative angles on average were 179.2°±2.9 for the HKA, 89.9°±1.6 for the MDFA and 89.0°±2.3 for the MPTA. The average postoperative deviation from the target values was 2.22°±2.14 for the HKA angle, 1.07°±1.15 for the MDFA and 1.66°±1.90 for the MPTA. There were no significant differences between the two groups in any of the measurements. The lower limb alignment goal was achieved in 50 cases (73%), with 41 of these achieved with PSCG (82%). Of the 18 cases where the target was not achieved, PSCG were used 16 times (88%). In this study cohort, lower limb alignment was not significantly closer to an HKA of 180° or achieved more often with the use of PSCG versus standard instrumentation. Since the results of the two groups can be superimposed, we found no evidence that use of PSCG improves postoperative lower limb alignment. Level of evidenceIV. Study typeCohort.

A prospective randomised controlled study of patient-specific cutting guides compared with conventional instrumentation in total knee replacement

Patient-specific cutting guides (PSCGs) are designed to improve the accuracy of alignment of total knee replacement (TKR). We compared the accuracy of limb alignment and component positioning after TKR performed using PSCGs or conventional instrumentation. A total of 80 patients were randomised to undergo TKR with either of the different forms of instrumentation, and radiological outcomes and peri-operative factors such as operating time were assessed. No significant difference was observed between the groups in terms of tibiofemoral angle or femoral component alignment. Although the tibial component in the PSCGs group was measurably closer to neutral alignment than in the conventional group, the size of the difference was very small (89.8° (sd 1.2) vs 90.5° (sd 1.6); p = 0.030). This new technology slightly shortened the bone-cutting time by a mean of 3.6 minutes (p < 0.001) and the operating time by a mean 5.1 minutes (p = 0.019), without tangible differences in post-operative blood loss (p = 0.528) or need for blood transfusion (p = 0.789). This study demonstrated that both PSCGs and conventional instrumentation restore limb alignment and place the components with the similar accuracy. The minimal advantages of PSCGs in terms of consistency of alignment or operative time are unlikely to be clinically relevant.