We present an analysis of manual and computer-assisted preoperative pedicle screw placement planning. Preoperative planning of 256 pedicle screws was performed manually twice by two experienced spine surgeons (M1 and M2) and automatically once by a computer-assisted method (C) on three-dimensional computed tomography images of 17 patients with thoracic spinal deformities. Statistical analysis was performed to obtain the intraobserver and interobserver variability for the pedicle screw size (i.e. diameter and length) and insertion trajectory (i.e. pedicle crossing point, sagittal and axial inclination, and normalized screw fastening strength). In our previous study, we showed that the differences among both manual plannings (M1 and M2) and computer-assisted planning (C) are comparable to the differences between manual plannings, except for the pedicle screw inclination in the sagittal plane. In this study, however, we obtained also the intraobserver variability for both manual plannings (M1 and M2), which revealed that larger differences occurred again for the sagittal screw inclination, especially in the case of manual planning M2 with average differences of up to 18.3°. On the other hand, the interobserver variability analysis revealed that the intraobserver variability for each pedicle screw parameter was, in terms of magnitude, comparable to the interobserver variability among both manual and computer-assisted plannings. The results indicate that computer-assisted pedicle screw placement planning is not only more reproducible and faster than, but also as reliable as manual planning

Aims. Navigation devices are designed to improve a surgeon’s accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error. Methods. A total of 356 patients undergoing primary THA were prospectively enrolled from November 2016 to March 2018. Clinically relevant error using the CAS system was defined as a difference of > 5° between CAS and 3D radiological reconstruction measurements for acetabular component inclination and anteversion. Univariate and multiple logistic regression analyses were conducted to determine whether hypermobile (. Δ. sacral slope(SS). stand-sit. > 30°), or stiff (. ∆. SS. stand-sit. < 10°) spinopelvic mobility contributed to increased error rates. Results. The paired absolute difference between CAS and postoperative imaging measurements was 2.3° (standard deviation (SD) 2.6°) for inclination and 3.1° (SD 4.2°) for anteversion. Using a target zone of 40° (± 10°) (inclination) and 20° (± 10°) (anteversion), postoperative standing radiographs measured 96% of acetabular components within the target zone for both inclination and anteversion. Multiple logistic regression analysis controlling for BMI and sex revealed that hypermobile spinopelvic mobility significantly increased error rates for anteversion (odds ratio (OR) 2.48, p = 0.009) and inclination (OR 2.44, p = 0.016), whereas stiff spinopelvic mobility increased error rates for anteversion (OR 1.97, p = 0.028). There were no dislocations at a minimum three-year follow-up. Conclusion. Despite high reliability in acetabular positioning for inclination in a large patient cohort using an optical CAS system, hypermobile and stiff spinopelvic mobility significantly increased the risk of clinically relevant errors. In patients with abnormal spinopelvic mobility, CAS systems should be adjusted for use to avoid acetabular component misalignment and subsequent risk for long-term dislocation. Cite this article: Bone Jt Open 2022;3(6):475–484

Introduction. Risks and benefits of bilateral total knee arthroplasty (TKA), whether simultaneous, sequential single-staged, or staged is a topic of debate. Similarly, computer-assisted navigation for TKA is controversial regarding complications, cost-effectiveness, and benefits over conventional TKA. To our knowledge, no studies have compared computer-assisted and conventional techniques for sequential bilateral TKA. We hypothesise that the computer-assisted technique has fewer complications. Methods. We retrospectively reviewed 40 computer-assisted and 36 conventional bilateral sequential TKAs from 2007–2011 with 1 year follow-up for complications. Groups were matched by age, gender, body mass index (BMI), Charlson Comorbidity Index (CCI), and American Society of Anesthesiologists Classification (ASA). Pearson's Chi-square, Fisher's exact test, and independent samples t-test were used to compare groups. Results. Our populations' mean age was 65.9 years, BMI 31.6, CCI 3.4, ASA 2.3, and a male to female ratio of 1:2. Computer-assisted demonstrated significantly better postoperative day (POD) 1 hemoglobin (p=.001), decreased number of blood transfusions (p=.001) and fewer complications (p=.023). Mean preoperative hemoglobin (Hgb) for both groups was 12.4 g/dL, but mean POD1 Hgb was 10.2 g/dL and 9.3 g/dL, for computer-assisted and conventional groups respectively. Total blood transfusion units were a mean of 1.0 and 1.7 for computer-assisted and conventional groups respectively. Seven (19%) patients in the conventional group had lethargy, altered mental status (AMS), or syncope versus none in the computer-assisted group. Subsequent Hgb levels, tourniquet time, length of stay, readmissions, and reoperations were not significantly different with numbers available between the two groups. Conclusion. Computer-assisted sequential bilateral TKAs had higher Hgb on POD1 and lower blood transfusions and complications. This may be due to violation of the femoral canal causing increased bleeding using the conventional technique. Fat emboli from the femur may have caused AMS, but did not increase incidence of pulmonary embolism in the conventional group

Introduction. Re-revision due to instability and dislocation can occur in up to 1 in 4 cases following revision total hip arthroplasty (THA). Optimal placement of components during revision surgery is thus critical in avoiding re-revision. Computer-assisted navigation has been shown to improve the accuracy and precision of component placement in primary THA; however, its role in revision surgery is less well documented. The purpose of our study was to evaluate the effect of computer-assisted navigation on component placement in revision total hip arthroplasty, as compared with conventional surgery. Methods. To examine the effect of navigation on acetabular component placement in revision THA, we retrospectively reviewed data from a multi-centre cohort of 128 patients having undergone revision THA between March 2017 and January 2019. An imageless computer navigation device (Intellijoint HIP®, Intellijoint Surgical, Kitchener, ON, Canada) was utilized in 69 surgeries and conventional methods were used in 59 surgeries. Acetabular component placement (anteversion, inclination) and the proportion of acetabular components placed in a functional safe zone (40° inclination/20° anteversion) were compared between navigation assisted and conventional THA groups. Results. Mean inclination decreased post-operatively versus baseline in both the navigation (44.9°±12.1° vs. 43.0°±6.8°, p=0.65) and control (45.8°±19.4° vs. 42.8°±7.1°, p=0.08) groups. Mean anteversion increased in both study groups, with a significant increase noted in the navigation group (18.6°±8.5° vs. 21.6°±7.8°, p=0.04) but not in the control group (19.4°±9.6° vs. 21.2°±9.8°, p=0.33). Post-operatively, a greater proportion of acetabular components were within ±10° of a functional target (40° inclination, 20° anteversion) in the navigation group (inclination: 59/67 (88%), anteversion: 56/67 (84%)) than in the control group (49/59 (83%) and 41/59, (69%), respectively). Acetabular component precision in both study groups improved post-operatively versus baseline. Variance in inclination improved significantly in both control (50.6° vs. 112.4°, p=0.002) and navigation (46.2° vs. 141.1°, p<0.001) groups. Anteversion variance worsened in the control group (96.3° vs. 87.6°, p=0.36) but the navigation group showed improvement (61.2° vs. 72.7°, p=0.25). Post-operative variance amongst cup orientations in the navigation group (IN: 46.2°; AV: 61.2°) indicated significantly better precision than that observed in the control group (IN: 50.6°, p=0.36; AV: 96.3°, p=0.04). Discussion. Re-revision is required in up to 25% of revision THA cases, of which 36% are caused by instability. This places a significant burden on the health care system and highlights the importance of accurate component placement. Our data indicate that the use of imageless navigation in revision THA – by minimizing the likelihood of outliers – may contribute to lower rates of re-revision by improving component orientation in revision THA. Conclusion. Utilizing imageless navigation in revision THAs results in more consistent placement of the acetabular component as compared to non-navigated revision surgeries

Utilization of C-arm fluoroscopy during direct anterior total hip arthroplasty (THA) is disruptive and potentially increases the risks of patient infection and cumulative surgeon radiation exposure. This pilot study evaluated changes in surgeon C-arm utilization during an initial 10 cases of direct anterior THA in which an imageless computer-assisted navigation device was introduced. This retrospective study includes data from 20 direct anterior THA cases performed by two orthopaedic surgeons (BC; SRE) in which an imageless computer-assisted navigation device was utilized (Intellijoint HIP®; Intellijoint Surgical, Waterloo, ON, Canada). Total C-arm image count was recorded in each case, and cases were grouped in sets of 5 for each surgeon. The mean C-arm image count was calculated for each surgeon, and combined C-arm image counts were calculated for the study cohort. Student's t-tests were used to assess differences. The use of intraoperative C-arm fluoroscopy decreased from a mean of 9.4 images (standard deviation [SD]: 8.6; Range: 3 – 23) to a mean of 2 images (SD: 2.9; Range: 0 – 7) for surgeon BC (P=0.10) and decreased from a mean of 10.75 images (SD: 1.2; range 9 – 12) to a mean of 6.7 images (SD: 8.3; range: 0 – 16) for surgeon SRE (P=0.36). Combined, an overall decrease in intraoperative C-arm image count from a mean of 11.3 images (SD: 6.9; range: 6 – 23) to a mean of 3.7 images (SD: 3.9; range: 0 – 8.5) was observed in the study cohort (P=0.06). The adoption of imageless computer-assisted navigation in direct anterior THA may reduce the magnitude of intraoperative C-arm fluoroscopy utilization; however further analysis is required

Hip resurfacing has recently become an alternative for total hip replacement, especially for younger and more active patients. Although early results are encouraging, there are reports of failure as a result of malpositioning of the femoral component. To help overcome this problem we developed a CT-guided computer-assisted system for the planning and guidance of the femoral component during hip resurfacing. 3D isosurface models were generated from a CT scan of the pelvis and proximal femur. By superimposing virtual prosthetic components, the surgeon preoperatively determined the size, position and orientation of the femoral component. Intraoperatively, an optoelectronic navigation system was used for realtime CT-guidance of the insertion of the alignment pin for the femoral component. In a laboratory study, the precision of the intraoperative guidance system was investigated. One experienced and one inexperienced surgeon performed one posterior and one anteriolateral approach on 10 different plastic bone models. After each procedure, the alignment-pin orientation was compared to the planned orientation. In a preliminary clinical study, 27 patients underwent the computer-assisted method and 13 patients were operated on using conventional technique. Both posterior and anteriolateral surgical approaches were used. Pre-operative and postoperative neck-shaft angles were compared using Student’s t-test. In the laboratory study, the mean deviations between planned and navigated alignment-pin orientation was 0.65° (StDev 0.9°) for the experienced surgeon, and 0.13° (StDev 0.7°) for the inexperienced surgeon. The mean deviation of anteversion angles were measured as 0.31° (StDev 0.8°) for the experienced surgeon and 0.01° (StDev 0.9°) for the inexperienced surgeon. In the clinical study, we measured the neck-shaft angle in the computer-assisted group to be an average of 133° preoperatively and 134° postoperatively (p=0.16), and in the conventional group to be an average of 136° pre-operatively and 135° postoperatively (p=0.79). There were no significant differences between pre-operative and post-operative measurements between the groups. However, there was a significantly lower standard deviation in the postoperative computer-assisted group: it was 6.6°, compared to 13.3° in the conventional group (Levene’s test for equality of variances, p=0.004). We conclude, based on our results, that a CT-guided system can help to prevent femoral misalignment during a hip resurfacing by increasing the intraoperative precision

Purpose: This in-vitro study was conducted to assess the effect of a computer-assisted method of performing shoulder hemiarthroplasty, in comparison to traditional techniques, on passive glenohumeral joint kinematics during abduction. Methods: Seven pairs of fresh-frozen cadaveric shoulders were tested. One specimen from each pair was randomized to the computer-assisted technique, while the contralateral shoulder underwent a traditional hemiar-throplasty using standard surgical guides by an experienced shoulder surgeon. A simulated four-part proximal humerus fracture was created in each shoulder and was reconstructed using a modular shoulder hemiarthroplasty system (Anatomical Shoulder Hemiarthroplasty System, Centrepulse Orthopaedics Inc, Austin, TX). CT data and computerized simulations of anatomical characteristics were used in the computer-assisted technique. An electromagnetic tracking device (Flock of Birds, Ascension Technologies, Burlington, VT) in conjunction with custom-written software (LabVIEW, National Instruments, Austin, TX) enabled real-time intra-operative feedback.||Passive abduction of the glenohumeral joint was conducted and the resulting motion was quantified using the aforementioned tracking device. Coordinate systems, created on both the humerus and scapula from digitized anatomical landmarks, were used to transform the kinematic data into clinically relevant parameters. Statistical analyses were performed using one-way Analyses of Variance (ANOVAs) followed by post-hoc Student-Newman-Keuls multiple comparisons (p< 0.05). Results: In the superior-inferior direction, a significant difference in joint kinematics (p=0.011) was found between the computer-assisted and the traditional technique, with the traditional technique resulting in a more inferiorly positioned humeral head at all angles of elevation. There was no difference in translation between the native shoulders and the computer-assisted hemiarthroplasty (p> 0.05). In the anterior-posterior direction there was no difference measured in the position of the humeral head between the two surgical techniques, which were both similar to the native shoulder (p> 0.05). Conclusions: This is the first known study to examine the effects of a computer-assisted method for performing shoulder hemiarthroplasty. Our results show that the computer-assisted approach should allow improved restoration of glenohumeral joint kinematics relative to conventional techniques, potentially resulting in improved patient outcomes and implant durability

Purpose of the study: Anterior cruciate ligament (ACL) navigation systems are based on two underlying principles: «statistical» anatomic position and isometric anatomic (anatomometric) positioning. The purpose of this study was to demonstrate that an anatometric positioning of the transplant can be achieved, in other words, that the transplant can be positioned in the original anatomic air of the ligament insertion while preserving an optimal isometry without notch impingement. This study was also conducted to compare conventional systems with a computer-assisted system. Material and methods: This study was conducted on thawed fresh-frozen cadaver knee specimens with > 120° flexion. The computer-assisted protocol for ACL surgery was applied to ten knee specimens. The original anatomic insertions of the ACL were dissected then inserted at the appropriate points into the computer display. The tibial and femoral insertion points of two classical aiming devices were recorded. These points were compared with the original anatomic insertion. Results: For the tibia: classical aiming methods proposed a point of insertion posterior to the anatomic insertion for eight knees and within the frontiers of the anatomic insertion for two, in line with the anterior border of the posterior cruciate ligament. The computer-designated point of insertion for the tibial fixation was always within the anterior third of the ACL insertion, generally medially. For the femur, the transition (or isometric) line ran across the anatomic femoral insertion in all knees. It was observed that in all cases, the surgeon could choose an anatomic insertion with lesser anisometry by situating the insertion in the distal part of this line: for nine knees, the computer-designated femoral point was anatomic and with lesser anisometry. The Acufex aiming device produced better anisometry (my=4 mm) than the Arthrex device (my=6 mm) but with a less favorable anisometry curve. Discussion: The notion of anatometry is compatible with computer-assisted surgery. This study demonstrated that the computer-designated tibial point of insertion is more anterior and medial than the conventional aiming points. This is a potential choice if the absence of a notch impingement can be visualized: Howel described a manual fluoroscopic method. In our opinion, at the present time, optimal choice of the femoral point to achieve the desired anisometric curve is strictly operator-dependent

The success of total knee replacement depends on several factors, however, surgical technique is particularly important. In fact mistakes in alignment of prosthtic components are common causes of aseptic loosening. Serious improper alignment (more than 3°) was found out, according to several papers, in about 10% of the implants; this appears not correlated with surgeon’s experience when they use mechanical alignment devices either extra medullary or intra medullary. The development of computer-based systems to achieve correct prosthetic components alignement has the purpose to solve the problems of traditional mechanical alignement systems. At present computer-assisted navigation systems, either they areimage-free or imege-based, are widely empolied while robotic systems are not so commonly used. The Authors describe in this paper the features of the computer-assisted navigation system they at present employ. They moreover emphasize its precision and the reproducibility of the results they can achive. The features of this system (it is based on an image-free navigation method; it allows quantification of the kinematics of the knee; it allows the use of either specially designed cutting bolcks or standar instruments), are an intresting evolution of computer-assisted navigation systems for knee replacement

Purpose: Most revisions of total knee arthroplasty (TKA) occur before the fifth year. The leading cause is prosthesis malalignment. Computer-assisted surgery is presented as a technique which improves implantation precision. The purpose of this study was to evaluate the radiographic quality of computer-assisted TKA implantation in comparison with conventional implantation. Material and methods: A prospective randomised study was conducted with a total of 82 patients assigned randomly to conventional instrumentation (group 1) or computer-assisted implantation (group 2). The two groups were comparable for age, gender, body mass index, side, and preoperative femorotibial angle (HKA). The same surgeon operated all patients using the same cemented posterostabilised prosthesis. Radiographically, the HKA, the theta angle between the mechanical and anatomic femoral axis, the angle of the femoral and tibial implantations, and the posterior tibial slope were noted. All measures were taken by an independent operator who was unaware of the operative technique. Results: There was no statistical difference in the HKA 177.5° in group 1 and 179.2° in group 2 (p=0.13); the theta angle was 6° in group 1 and 5.9° in group 2 (p=0.78); the femoral implantation angle was 90.3° in group 1 and 90° in group 2 (p=0.74); the posterior tibial slope was 3.5° in group 1 and 3.15° in group 2 (p=0.65). There was a statistical difference in the tibial angle, 87.3° in group 1 and 89° in group 2 (p=0.012). Discussion: This study demonstrates a significant improvement in the navigation group for the position of the tibial implant and no difference for the femoral implant. This might be related to the cut guide which allowed more intra-operative adjustment for the tibia. Blood loss was equivalent in the two groups (503 mg) and operative time was longer in the navigation group (18 minutes). Conclusion: It appears important to have specifically adapted cut guides for computer-assisted surgery and to reduce operative time

While double-bundle anterior cruciate ligament (ACL) reconstruction attempts to recreate the two-bundle anatomy of the native ACL, recent research also indicates that double-bundle reconstruction more closely reproduces the biomechanical properties of the ACL and restores the rotatory and sagittal stability to the level of the intact knee that was not attainable with anatomic single-bundle reconstruction. Though double-bundle reconstruction provides these potential biomechanical benefits, it poses a significant challenge to the surgeon who must attempt to accurately place twice as many tunnels while avoiding tunnel convergence compared to single-bundle reconstruction. In addition, previous work has shown that tunnel malpositioning may cause grafts that fail to reproduce the native biomechanics of the ACL, increase graft tension in deep knee flexion, increase anterior tibial translation, and produce lower IKDC (International Knee Documentation Committee) scores. We hypothesise that experienced surgeons without the use of computer-assisted navigation will place tunnels on the tibial plateau and lateral femoral condyle that more closely emulate the locations of the native anteromedial (AM) and posterolateral (PL) ACL bundles than inexperienced surgeons with the use of computer-assisted navigation. A novice surgeon group comprised of three medical students each performed double-bundle ACL reconstruction using passive computer-assisted navigation on a total of eleven cadaver knees. Their individual results were compared to three experienced orthopaedic surgeons each performing the identical procedure without the use of computer-assisted navigation on a total of nine cadaver knees. There were no significant differences in placement of either the AM or PL tunnels on the tibial plateau between novice surgeons using computer-assisted navigation and experienced surgeons without the use of computer navigation. On the lateral femoral condyle, novice surgeons placed the AM and PL tunnels significantly more anterior along Blumensaat's line on average compared to experienced surgeons. Both groups placed femoral AM and PL tunnels anterior to previously described AM and PL bundle positions. Novice surgeons utilizing computer-assisted navigation and experienced surgeons without computer assistance place the AM and PL tunnels on the tibial side with no significant difference. On the lateral femoral condyle, novice surgeons utilising computer-assisted navigation place tunnels significantly anterior along Blumensaat's line compared to experienced surgeons without the use of computer navigation

Background. Both minimally invasive surgery(MIS) and computer-assisted surgery(CAS) in total knee arthroplasty have been scientifically linked with surgical benefits. However, the long-term results of these techniques are still controversial. Most surgeons assessed the surgical outcomes with regard to knee alignment and range of motion, but these factors may not reflect subjective variables, namely patient satisfaction. Purpose. To compare satisfaction and functional outcomes between two technical procedures in MIS total knee arthroplasty, namely computer-assisted MIS and conventional MIS procedure, operated on a sample group of patients after 10 years. Methods. Seventy cases of posterior-stabilized total knee prostheses were implanted using a computer-assisted system and were compared to seventy-four cases of matched total knee prostheses of the same implant using conventional technique. Both groups underwent arthrotomy by 2 centimeter limited quadriceps exposure minimally invasive surgery (2 cm Quad MIS). At an average of ten years after surgery, self-administered patient satisfaction and WOMAC scales were administered and analyzed. Results. Demographic data of both groups including sex, age, preoperative WOMAC and post-operative duration were not statistically different. Post-operative WOMAC for the computer-assisted group was 38.94±5.68, while the conventional one stood at 37.89±6.22. The median of self-administered patient satisfaction scales of the computer-assisted group was 100 (min37.5-max100), while the conventional one was 100 (min25-max100). P-value was 0.889. There was 1 re-operative case in the conventional MIS group due to peri-prosthetic infection which was treated with debridement, polyethylene exchanged and intravenous antibiotics. Conclusion. The long-term outcomes of computer-assisted MIS total knee arthroplasty are not superior to that of the conventional MIS technique. Computer assisted MIS total knee arthroplasty is one of the treatment options for osteoarthritis of the knee that has comparable levels of satisfaction to the conventional MIS technique

Acetabular component malpositioning increases the risk of impingement, dislocation, and wear. The goal of computer-assisted techniques is to improve the accuracy of component positioning, in particular optimizing the orientation of the acetabular cup. The goal of the current study was to measure accuracy of cup placement in a large clinical series of hips that underwent CT-based computer-assisted THA. 146 hips in 140 patients underwent CT-based computer-assisted THA between 2006 and 2008. In all cases cup orientation was planned according to the individual preoperative CT and the anterior pelvic plane with an inclination of 41° and anteversion of 30°. For the procedure, all patients were placed in the lateral position and the cup was implanted using angled instruments. Intra-operatively all cases were navigated using an optoelec-tronic camera and tracked instruments (Vector Vision prototype, BrainLab, Germany). Post-operatively, cup orientation was measured using a previously validated technique of 2D/3D-matching using the preoperative CT and post-operative radiographs. This technique allows for accurate measurement of cup position from plain radiographs corrected for individual pelvic orientation. The mean accuracy for inclination was −2.5° ± 4.0° (−12° – 10°) and for anteversion it was 0.7° ± 5.3° (−11° – 15°). In 2 hips (1.4%) a deviation of more then 10° in inclination and in 4 hips (2.7%) a deviation of more then 10° in anteversion were found. The current study demonstrates that the acetabular component can routinely be implanted with the assistance of CT-based navigation with reasonable agreement between the navigation measurements of component orientation at the time of surgery. Nonetheless, outliers still occasionally occur. These might be due to unrecognized loosening of the pelvic reference base, inaccurate registration or the use of the ipsilateral surface-based registration algorithms which rely heavily on points near the center of rotation of the hip

Purpose: Total knee arthroplasty has been established as a reliable treatment modality for advanced gonarthrosis. Satisfactory outcome depends on restoration of the neutral alignment of the leg. Our study evaluates whether computer-assisted navigated knee arthroplasty achieves a more accurate knee alignment. Materials and Methods: In a prospective study two groups of 24 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique. Limb alignment and component orientation were determined on post-operative coronal and lateral X-rays. Results: In our study the post operative axis of the thumb was significantly better in the computer-assisted group (94%, within ±3. °. varus/valgus) compared with the conventional group (82%, within ±3° varus/valgus). A significantly better orientation of the femoral and the tibial components was achieved in the computed-assisted navigated group. Conclusions: Computer-assisted navigated TKA gives better correction of leg alignment and components orientation as we saw in the computer-assisted navigated group. Potential benefits in the long-term outcome and functional improvement require further investigation

Background: Whether total knee arthroplasty using computer-assisted surgical navigation can improve the limb and component alignment is a matter of debate. We hypothesized that total knee arthroplasty using computer-assisted surgical navigation is superior to the conventional total knee arthroplasty with regard to the precision of implant positioning. Methods: Sequential simultaneous bilateral total knee arthroplasties were carried out in 160 patients (320 knees). One knee was replaced using a computer-assisted surgical navigation system and the other conventionally without using computer-assisted surgical navigation. The two methods were compared for accuracy of orientation and alignment of the components determined by radiographs and computed tomographs. The mean follow-up was 3.4 years. Results: The mean preoperative Knee Society score was 26 points in the computer-assisted total knee arthroplasty group, which was improved to 92 points postoperatively and it was 25 points, which improved to 93 points post-opertively in the conventional total knee arthroplasty group. Ranges of motion of the knees were similar in both groups. The operating and tourniquet times were significantly longer in the computer-assisted total knee arthroplasty group than in the conventional total knee arthroplasty group (P< 0.001). Accuracy and the number of outliers of component position between the two groups were not significantly different (P> 0.05). Conclusions: Our data demonstrated that total knee arthroplasty using computer-assisted surgical navigation did not result in more accurate implant positioning than that achieved in conventional total knee arthroplasty, determined by both radiographs and computed tomographs

Abstract Detail. Interim results on a prospective, randomised, single-blinded pilot study to compare implant alignment using a patient-matched cutting guide versus a computer-assisted navigation system following total knee arthroplasty. Purpose of Study. To compare implant alignment using a patient-matched cutting guide (Visionaire) versus a computer-assisted navigation system (CAS) following total knee arthroplasty (TKA). Description of methods. Ethics approval was sought and granted by the South African Medical Association Research Ethics Committee. Patient consent for participation was obtained. Patients were randomized to TKA using Visionaire or CAS. Mechanical alignment was evaluated pre-operatively and at 3 months with a full leg X-Ray. Operative and post-operative parameters relating to resource utilization were captured. Clinical status according to the Knee Society Clinical Rating System (KSCRS) was assessed pre-operatively and at 3 months. Adverse events were noted. An independent Contract Research Organisation was used to monitor the site. Summary of results. Ten unique patients were enrolled, of whom 5 were randomized to Visionaire and 5 to CAS. Two patients in the Visionaire group have not yet reached their 3-month assessment. No significant difference in mechanical alignment between the 2 groups at 3 months was observed. The median duration of surgery was significantly shorter for the patient-matched cutting guide group across all assessed parameters (theatre time: 117 versus 150 minutes, p=0.009; operative time: 85 versus 108 minutes, p=0.0088; tourniquet time: 73 versus 99 minutes, p=0.009; and anaesthetist time: 117 versus 150 minutes, p=0.009). No other significant differences in operative or post-operative cost-drivers were noted between the 2 groups. No significant difference in KSCRS scores between the 2 groups at 3 months was observed. Two adverse were reported, one in each group, both unrelated to the medical devices, and both of which have resolved. Conclusion. While implant alignment appears consistent and comparable in both groups at 3 months, the median duration of surgery was significantly shorter for the Visionaire group. DISCLOSURE: Assistance and funding was received from Smith & Nephew

Malalignment in total knee replacement (TKR) is frequently associated with early failure and poor functional results. It has been suggested that errors in tibial and femoral alignment of > 3° occurs in at least 10% of TKR. Since 1999 we have been using a computer-based alignment system (Orthopilot;Aesculap,Tuttlingen,Germany) for TKR in more than 300 implants. The aim of this retrospective study is to present our experience in comparison with traditional alignment systems for TKR. Patients receiving TKR with different alignment systems were enrolled in the study and assigned to three different groups. In group A (38 cases) TKR was performed using a computer-assisted alignment system, in group B (40 cases) TKR was performed using a totally intramedullary alignment system and in group C (37 cases) TKR was performed using a totally extramedullary alignment system. The criteria for inclusion were a diagnosis of primary osteoarthritis, a pre-operative mechanical frontal axis (MFA) ranging from 165° to 195°, and a pre-operative knee flexion deformity not exceeding 10° calculated according to pre-operative radiographs. The radiographs were assessed for the alignment of the femoral and tibial component and the lower limb alignment, considering the lateral femoral component angle (FCA), the medial tibial component angle (TCA), respectively. The surgical time was statistically longer in the computer-assisted group. The results did not show statistically significant differences in FCA, TCA and MFA among the three groups. However, in the extramedullary aligned group there was a statistically higher percentage of TKRs with both an abnormal FCA and MFA compared to the computer-based alignment group. Furthermore, in the computer-based alignment group all the implants were aligned within 4° of an ideal MFA. Our results demonstrate the significant improvement in the accuracy of implant alignment using a computer-assisted system compared to an extramedullary one. Furthermore, we underline how stressing the knee during all the phases of the registration process for the navigated implant can demonstrate how much of the deformity can be corrected and thus guide the soft-tissue release

Introduction. Computer-assisted navigation is an established tool in hip and knee arthroplasty. This technology was introduced with the goals of greater precision in bone preparation and implant placement, potentially leading to improved clinical outcomes. Various navigation protocols exist, many of which require placement of temporary percutaneous pins in the operative field. Risks of pin placement have not been described. Methods. We conducted a retrospective review of 352 consecutive patients undergoing elective hip and knee surgery using computer-assisted navigation between January 2013 and December 2015, all with a minimum follow-up of 90 days. Navigation pins were placed using a standardized protocol into the iliac crest for hip arthroplasty or into the femoral and tibial diaphysis for knee arthroplasty. Postoperatively, all patients were allowed to weight bear as tolerated. Patient records were reviewed for operative details and clinical outcomes. Outcome measures included any pin site complications including direct neurovascular damage, fracture through a pin site, and pin site infection. Results. A total of 968 pin sites were included in the study. Two pin site complications were reported (0.21%). No neurovascular injuries were reported from pin placement (0.0%). No periprosthetic fractures through a pin site were reported (0.0%). Two patients developed a pin-site infection with purulent drainage (0.21%), both of which resolved with oral antibiotics and local wound care. Conclusion. Potential benefits of navigation in hip and knee arthroplasty are still being investigated, however the placement of pins required for this technology are associated with minimal patient morbidity and should be considered a safe intervention with minimal added risk

Aims: All health care systems in the developed world are facing everincreasing health care costs and faced with this prospect, governments and other health care payers seek greater beneþts from existing health resources. An inexpensive alternative without excessive technical demands on physicians or operating room personnel, is two-dimensional (2D) computerassisted preoperative planning. The purpose of the study was to clinically validate the SYMBIOS X-Rays Preoperative Planning software for preoperative planning of cementless total hip replacement. Methods: For each of the thirty patients with osteoarthritis who underwent a total hip arthroplasty using an uncemented anatomic stem, the manual preoperative planning of the surgeon, the 2D computer-assisted one and the result after the real implantation were compared by an independent observer. Comparisons were based on stem and neck sizes as well as stem and rotation center position, using the deþnitive implantation as the reference standard. Results: There were no statistical differences between the results of the manual and 2D computer-assisted preoperative plans in terms of stem size and neck length (< 1 size) as well as for rotation center positioning (< 5mm) when compared to the deþnitive implantation. Conclusion: Two-dimensional computer-assisted preoperative planning seems to provide results as good as those of the manual procedure with the great advantage of allowing the surgeon to simulate various stem designs and to take into account biomechanical criteria

Introduction:. Computer-assisted surgery (CAS) aims to improve component positioning and mechanical alignment in Total Knee Arthroplasty (TKA). Robotic cutting-guides have been integrated into CAS systems with the intent to improve bone-cutting precision and reduce navigation time by precisely automating the placement of the cutting-guide. The objectives of this study were to compare the intra-operative efficiency and accuracy of a robotic-assisted TKA procedure to a conventional computer-assisted TKA procedure where fixed sequential cutting-blocks are navigated free-hand. Methods:. This was a retrospective study comparing two distinct cohorts: the control group consisted of patients undergoing TKA with conventional CAS (Stryker Universal Knee Navigation v3.1, Stryker Orthopaedics, MI) from May 2006 to September 2007; the study group consisted of patients undergoing TKA with a robotic cutting-guide (Apex Robotic Technology, ART, OMNIlife Science, MA) from October 2010 to May 2012. Exclusion of patients with preexisting hardware in the joint or an absence of navigation data resulted in a total of 29 patients in the control group and 52 patients in the study group. Both groups were similar with respect to BMI, age, gender, and pre-operative alignment. All patients were operated on by a single surgeon at a single institution. The navigation log files were analyzed to determine the total navigation time for each case, which was defined as the time from the start of the acquisition of the hip center to the end of the final alignment analysis for both systems. The intraoperative final mechanical axis was also recorded. The tourniquet time (time of inflation prior to incision to deflation immediately after cement hardening) and hospitalization length were compared. Linear regression analysis was performed using R statistical software v2.12.1. Results:. Navigation times were on average 9.0 minutes shorter in the study group compared to the control group (95% CI: [4.0, 14.1], p = 0.0006). Average absolute intraoperative alignment was 0.5 degrees closer to neutral in the robotic group compared to the conventional CAS group (95% CI: [0.08, 0.95], p = 0.020). Tourniquet time was not significantly different between the two systems (0.2 min, 95% CI [−5.4, 5.9], p = 0.926). Patients in the study group were discharged 0.6 days earlier than patients in the control group (95% CI: [0.1, 1.1], p = 0.0122). Discussions:. Our results suggest that use of a robotic cutting-guide can decrease the time taken to navigate a TKA procedure in comparison to conventional free-hand navigation of multiple fixed cutting blocks, which is supported by previous studies [1]. However, this time savings did not translate into a reduction in the tourniquet time. We believe this may be due in part to the two different types of bone cement that were used during the distinct study periods, where the hardening time for the cement in the study group was estimated to be approximately 5 minutes longer. Conclusions:. In one surgeon's hands, use of a robotic cutting-guide decreased navigation time, improved intraoperative final alignment, and decreased hospitalization length when compared to conventional computer-assisted navigation in TKA