Are robotic-assisted and computer-navigated total hip arthroplasty associated with superior outcomes in patients who have hip dysplasia?

Introduction

Robotic-assisted (RA) and computer-navigated (CN) total hip arthroplasty (THA) have been demonstrated to improve component placement accuracy compared to manual THA (mTHA) for primary osteoarthritis. As hip dysplasia presents several additional challenges in component placement accuracy and leg length discrepancy (LLD) correction during THA, a systematic review was conducted to evaluate whether utilizing these platforms may be associated with superior outcomes over mTHA in patients who have hip dysplasia.

Methods

PubMed, Medline, EBSCOhost, and Google Scholar were searched on September 13, 2023 to identify comparative studies published after January 1, 2000 that evaluated outcomes of RA-THA or CN-THA in patients who have hip dysplasia. The query yielded 197 unique articles, which were screened for alignment with the study aims. After screening, 10 studies fulfilled all inclusion criteria, comprising 946 patients. Risk of bias was evaluated via the Methodological Index for Nonrandomized Studies tool, and the mean score was 21.2 ± 1.5.

Results

Both RA-THA and CN-THA were not associated with improved acetabular anteversion and inclination when evaluating Crowe I-IV types altogether compared to mTHA, but studies reported improved accuracy for each Crowe I and II cases when assessed individually. While studies reporting acetabular cup placement within the Lewinnek and Callanan safe zones consistently found higher odds of accurate positioning for RA-THA versus mTHA, accuracy in achieving targeted center of rotation was mixed. Also, studies reported no difference in LLD restoration for RA-THA and CN-THA compared to mTHA. While operative time may be increased when utilizing these platforms, they may also expedite specific sequences, offsetting most of the increase in operative time.

Conclusion

This review highlights the advantages of RA-THA and CN-THA for patients who have DDH, particularly when treating Crowe I and II types as superior radiographic outcomes were achieved with these intraoperative technologies. However, there remains a need for studies to investigate whether this results in patient-reported outcome measures.

Navigating the learning curve: assessing caseload and comparing outcomes before and after the learning curve of computer-navigated total hip arthroplasty

PURPOSE

Computer-navigated (CN) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting a novel platform challenging. Therefore, we conducted a systematic review to assess the learning curve associated with CN-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA).

METHODS

A search was conducted using PubMed, MEDLINE, EBSCOhost, and Google Scholar on June 16, 2023 to find research articles published after January 1, 2000 (PROSPERO registration: CRD4202339403) that investigated the learning curve associated with CN-THA. 655 distinct articles were retrieved and subsequently screened for eligibility. In the final analysis, nine publications totaling 847 THAs were evaluated. The Methodological Index for Nonrandomized Studies (MINORS) tool was utilized to evaluate the potential for bias, with the mean MINORS score of 21.3 ± 1.2.

RESULTS

CN-THA showed early advantages to M-THA for component placement accuracy and radiographic outcomes but longer operative times (+ 3- 20 min). There was a learning curve required to achieve peak proficiency in these metrics, though mixed methodologies made the required caseload unclear.

CONCLUSIONS

CN-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes, though CN-THA's advantages become more pronounced with experience. Surgeons should anticipate longer operative times during the learning curve for CN-THA, which lessen following a modest caseload. A more thorough evaluation of novel computer-navigated technologies would be enhanced by adopting a more uniform method of defining learning curves for outcomes of interest. Registration PROSPERO registration of the study protocol: CRD42023394031, 27 June 2023.

Anterior cortical line of femur and tibia is more accurate than mid-shaft line to determine knee extension angle relative to sagittal mechanical axis during total knee arthroplasty

BACKGROUND

Accurate assessment of knee extension angle relative to sagittal mechanical axis (SMA) during TKA is usually obtained by computer navigation. Whether the lines along anterior cortex of distal femur and proximal tibia in short-knee imaging are accurate in determining knee extension angle has not been investigated.

METHODS

A prospective study was conducted on 106 patients (116 knees) who underwent primary TKA. After complete anesthetization, the leg was elevated 30° and short-knee lateral fluoroscopy was performed. The angles between the anterior cortical line (ACL), and between the mid-shaft line (MSL) of the femur and tibia, were measured. After surgical exposure and bony registration into OrthoPilot navigation system, the leg was elevated again and degree of knee extension was recorded. The angles determined using three methods were compared.

RESULTS

The mean extension angle observed by OrthoPilot (5.0° ± 6.8°, range -8°-25°) was not different from ACL method (5.3° ± 7.0°, range -8.1°-24.3°) (p = 0.811), but higher than MSL method (1.7° ± 7.1°, range -13.2°-18.1°) (p < 0.001). The mean absolute difference of ACL method from OrthoPilot was 0.2° ± 1.8° (range 0.0°-5.0°; 95%CI 0.0°-2.0°), and MSL method from OrthoPilot was 3.2° ± 2.6° (range 0.1°-8.2°; 95%CI 2.7°-3.7°). Measurement differences within 2° were found in 83.6% (97/116) and 37.9% (44/116) in the ACL and MSL method respectively (p < 0.001).

CONCLUSION

ACL of femur and tibia in a short-knee imaging is more accurate than MSL for determining knee extension angle relative to SMA. ACL can be assessed intraoperatively as the anterior cutting surface of distal femur after bone cut during TKA and the palpable anterior tibial crest. This ACL measurement in a pre- or postoperative radiograph provides the minimal detectable change of 3.5° and helpful in clinical research that requires high precision measurement.

Accelerometer-based portable navigation, a faster guide compared to computer-assisted navigation in bilateral total knee arthroplasty-a randomized controlled study

PURPOSE

There are limited studies in the literature comparing the alignment accuracy of  the large console, imageless, computer-assisted navigation (CAN) and portable, hand-held, accelerometer-based navigation (ABN) in total knee arthroplasty (TKA).  This study was aimed to compare the operative time, blood loss, radiological, clinical and functional outcomes between CAN- and ABN-guided bilateral TKA.

METHODS

From Jan 2016 to Dec 2017, 50 patients who underwent bilateral TKA were randomized to undergo either CAN-guided or ABN-guided TKA. Tourniquet time and blood loss were recorded, and intra-op complications were noted. Post-op radiological outcomes at 2 weeks were compared between the groups. The clinical and functional outcomes using the American Knee Society Scores (KSS) and Oxford Knee Score (OKS) were recorded pre-operatively and post-operatively at 3, 6, 12 months and at the end of the study with a minimum follow-up of 48 months.

RESULTS

Both groups were well-matched in terms of patient demographic parameters. The mean surgical time per knee was significantly lower in the ABN group (54.5 ± 5.6 min) compared to the CAN group (61.7 ± 13.7 min; p < 0.01). Mean blood loss per knee in the ABN group was 592.1 ± 245.3 mL compared to 682.8 ± 322.0 in the CAN group (p = 0.11). In the ABN group, the mean post-op mechanical axis was 1.2 ± 3.2° (vs 1.5 ± 2.2° in the CAN group, p 0.6), the frontal femoral angle was 88.8 ± 2.3° (vs 88.8 ± 1.8° in the CAN group, p 1.0) and frontal tibial angle was 90.1 ± 1.6° (vs 89.7 ± 1.1° in the CAN group, p 0.14). At 48 month follow-up, the mean functional KSS in the ABN group was 89.0 ± 5.7 (vs 88.1 ± 4.5 in the CAN group, p 0.37) and the mean OKS was 40.5 ± 2.8 (vs 39.6 ± 3.2 in the CAN group, p 0.12).

CONCLUSION

Portable, hand-held ABN offers alignment accuracy and functional outcomes in TKA similar to that with CAN, with a reduced duration of surgery. There was no advantage of either of the techniques in terms of clinical or functional outcomes at 48 month follow-up. LEVEL OF EVIDENCE 1.

Accuracy of the trough position in expansive open-door cervical laminoplasty using computer navigation techniques: a single-centre retrospective study

PURPOSE

This study aims to assess whether computer navigation can improve the accuracy of the trough position and clinical outcomes of expansive open-door cervical laminoplasty (EOLP).

METHODS

We reviewed a single centre of 28 conventional EOLP and 24 computer navigation EOLP cases. The conventional group had 102 laminae while the navigation group had 88. The distance from the medial cortex to the pedicle on the open-door side (OD) and hinge side (HD) was measured. Furthermore, the area of the spinal canal corresponding to each lamina before and after the surgical procedure was also measured. We then compared the differences in radiographic parameters and clinical outcomes between the two groups.

RESULTS

OD and HD were smaller in the navigation group compared to the conventional group, and the enlarged area of the spinal canal was larger in the navigation group than in the conventional group. The Japanese Orthopaedic Association (JOA) scores one year after the surgical procedure improved in both groups compared to the pre-operative period, and the JOA recovery rate was higher in the navigation group. The incidence of hinge fracture was lower in the navigation group, and the incidence of C5 palsy and axial pain was not statistically different between the two groups.

CONCLUSION

The use of computer navigation techniques has the potential to significantly improve the accuracy of EOLP compared to conventional procedures. It has been shown to more fully expand the spinal canal and contribute to clinical efficacy.

Fracture through tracking pin sites following a robotic-assisted total knee arthroplasty

The use of computer-navigated, robotic-assisted total knee arthroplasty (TKA) is expanding as the result of widespread efforts to improve the precision of implant placement and to restore mechanical, anatomic, and kinematic alignment. The procedure requires placement of femoral and tibial pins to mount the robotic tracking system. Fractures through tracking pin sites following robotic-assisted TKA are rare; only 30 cases have been reported to our knowledge. It is probable that this complication will become more frequent as the use of robotic-assisted TKAs continues to grow. We report the case of a 67-year-old female who suffered a fracture of the femur through two pin sites 3 months after a robotic-assisted TKA. We believe that this report is the first case in the radiologic literature. Our case demonstrates some of the difficulties of recognizing this complication and raises questions about appropriate post-operative imaging.

Computer Navigation for Revision Total Hip Arthroplasty Reduces Dislocation Rates

Purpose

Computer navigation in total hip arthroplasty (THA) offers potential for more accurate placement of acetabular components, avoiding impingement, edge loading, and dislocation, all of which can necessitate revision THA (rTHA). Therefore, the use of computer navigation may be particularly beneficial in patients undergoing rTHA. The purpose of this study was to determine if the use of computer-assisted hip navigation reduces the rate of dislocation in patients undergoing rTHA.

Methods

A retrospective review of 72 patients undergoing computer-navigated rTHA between February 2016 and May 2017 was performed. Demographics, indications for revision, type of procedure performed, and incidence of postoperative dislocation were collected for all patients. Clinical follow-up was recorded at 3 months, 1 year and 2 years.

Results

All 72 patients (48% female; 52% male) were included for analysis. The mean age was 70.4 ± 11.2 years and mean BMI was 26.4 ± 5.2 kg/m². 22 of 72 patients (31%) required a rTHA procedure due to instability resulting in dislocation. At 3 months, 1 year, and 2 years, there were no dislocations (0%). There was a significant reduction in dislocation rate after computer-navigated rTHA (0%) relative to that following primary THA in the same patient cohort (31%; p < 0.05).

Conclusion

Our study demonstrates a significant reduction in dislocation rate following rTHA with computer navigation. Although the cause of postoperative dislocation is often multifactorial, the use of computer navigation may help to curtail femoral and acetabular malalignment in rTHA.

Level of Evidence

Level III: retrospective.

Combined quadriceps tendon reconstruction and total knee replacement with computer navigation: a case report

Background

Chronic quadriceps tendon rupture is technically challenging for surgeons due to scarring and tendon retraction. The presence of concurrent ipsilateral knee osteoarthritis compounds the issue even further. Although a combined presentation is rare, treatment options to manage each coexisting pathology simultaneously are scarcely reported. We describe the case of a 67-year-old Caucasian male who had such a presentation, and was subsequently treated with a one-stage extensor mechanism autograft reconstruction and total knee replacement with computer navigation.

Case

The patient was a 67-year-old male Caucasian, who had previously sustained an acute rupture of his right quadriceps tendon that was adequately repaired 6 months prior. Despite an initial satisfactory result, he reported deterioration in his mobility in the few months thereafter, with worsening knee pain. His comorbidities consisted of hypertension, asthma, and a body mass index of 40.4 kg/m². Otherwise, there were no risk factors for tendon rerupture. Clinical examination later revealed a large palpable gap in the right suprapatellar region and weakness of active knee extension. No traumatic cause for this new presentation was identified. Suspicion of a chronic quadriceps tendon rupture was confirmed on radiological imaging, but the investigations also noted the presence of severe tricompartmental osteoarthritis of the ipsilateral, native knee joint. The combined procedure took place in one surgical sitting. The total knee replacement with patella resurfacing was performed first and assisted by computer navigation. The quadriceps tendon reconstruction was then conducted sequentially using the patient’s hamstring tendons (semitendinosus and gracilis). The tensile strength was reinforced with use of a Ligament Augmentation and Reconstruction System (LARS) ligament. Initial outcomes were excellent, and these results were maintained at 6 months postoperatively, with the patient reporting no pain and having full range of movement.

Conclusion

Our techniques used have not previously been reported, but are successful options in treating coexisting chronic quadriceps tendon rupture and ipsilateral knee osteoarthritis. The advantage of using computer navigation with an extramedullary femoral jig can lead to improved accuracy of bone cuts, which is important in the presence of anatomical disruption. Chronic failures of the extensor mechanism require different approaches depending on the inherent and underlying pathology. We feel that the multidisciplinary team approach to the management and use of two surgeons with differing expertise added to the successful outcome of this complex case.

Navigation and robotics improved alignment compared with PSI and conventional instrument, while clinical outcomes were similar in TKA: a network meta-analysis

PURPOSE

To achieve the desired alignment more accurately and improve postoperative outcomes, new techniques such as computer navigation (Navigation), patient-specific instruments (PSI) and surgical robots (Robot) are applied in Total Knee Arthroplasty (TKA). This network meta-analysis aims to compare the radiological and clinical outcomes among the above-mentioned techniques and conventional instruments (CON).

METHODS

A PRISMA network meta-analysis was conducted and study protocol was published online at INPLASY (INPLASY202060018). Three databases (PubMed, EMBASE and Cochrane) were searched up to June 1, 2020. Randomised controlled trials (RCTs) comparing any two of the four techniques were included. A Bayesian network meta-analysis was performed focusing on radiological and clinical outcomes. The odds ratio (OR) or mean difference (MD) in various outcomes were calculated, and the interventions were ranked by the surface under the cumulative ranking area (SUCRA) value.

RESULTS

Seventy-three RCTs were included, with a total of 4209 TKAs. Navigation and Robot could significantly reduce the occurrence of malalignment and malposition compared with PSI and CON, and Navigation could obtain higher medium-and-long-term KSS knee scores than CON. Robot had the greatest advantage in achieving the desired alignment accurately, followed by Navigation; Navigation had the greatest advantage in the KSS score.

CONCLUSION

Navigation and Robot did improve the accuracy of alignment compared with PSI and conventional instrument in TKA, but the above four techniques showed no clinical significance in postoperative outcomes.

LEVEL OF EVIDENCE

I.

Medial Open Wedge High tibial Osteotomy (MOWHTO) does not relevantly alter patellar kinematics: a cadaveric study

PURPOSE

The purpose of this study was to quantify the influence of medial open wedge high tibial osteotomy on patellar kinematics using optical computer navigation, as anterior knee pain infrequently occurs postoperatively and the reason is still being unknown.

METHODS

Ten medial open wedge high tibial osteotomies at supratuberosity level in 5 full body specimens were performed. The effect of the surgical procedure on patellar kinematics, measured at 5 and 10 degrees of leg alignment correction angle, was analyzed and compared to native patellar kinematics during passive motion-regarding patella shift, tilt, epicondylar distance and rotation. Linear mixed models were used for statistical analysis, a two-sided p value of ≤ 0.05 was considered statistically significant.

RESULTS

Tilt behavior, medial shift and epicondylar distance did not show a significant difference regarding natural patellar kinematics at both osteotomy levels. Both osteotomy correction angles showed a significant less external rotation of the patella (p < 0.001, respectively) compared to natural kinematics.

CONCLUSIONS

Except less external rotation of the patella, medial open wedge high tibial osteotomy does not seem to relevantly alter patellar alignment during passive motion. Future clinical studies have to prove the effect of MOWHTO on patellar kinematics measured in this experimental setup, especially regarding its influence on anterior knee pain.

Handheld computer-navigated constrained total knee arthroplasty for complex extra-articular deformities

INTRODUCTION

The present study aimed to assess the postoperative alignment and clinical outcomes of patients with complex extra-articular deformities (EADs) undergoing computer-assisted surgery (CAS) for constrained total knee arthroplasty (TKA) with modular stem extensions.

MATERIALS AND METHODS

From May 2015 to July 2018, ten patients with EADs scheduled for constrained TKA were enrolled retrospectively. The preoperative average deviation from neutral (= 180°) mechanical axis was 15.3° (range of coronal alignment: 150.9° varus-202.9° valgus). Alignment was assessed using an accelerometer-based handheld CAS system. On long-leg films, the positions of the components and possible stems were analysed and templated preoperatively. The average follow-up was 3.3 years (range: 2.0-4.6 years).

RESULTS

The postoperative mechanical axis was within ± 3.0° from neutral in nine patients. In all patients, the Knee Society score (KSS) and range of motion improved significantly. A constrained condylar and a rotating hinge prosthesis were used in five patients each. In eight patients, the 100-mm cementless stem that was preferred by the authors was found to be unusable for the femur or the tibia in the planning stage. For the femur, a cementless 100-mm stem was used in three, and a cemented 30-mm stem in five patients; a femoral stem was not usable in two patients. For the tibia, a cementless 100-mm stem was used in six, and a cemented 30-mm stem in two patients; a monoblock rotating hinge tibia was used in two patients.

CONCLUSIONS

Complex EADs were excellently managed during constrained TKA implantation using the handheld CAS system. Templating allowed the possible stem lengths to be identified and prevented anatomical conflict with the CAS-configured mechanical alignment. Limb alignment and function improved significantly after surgery. No intra- or postoperative complications occurred.

LEVEL OF EVIDENCE

Level IV, retrospective study.

After 25 years of computer-navigated total knee arthroplasty, where do we stand today?

Background

Limb and implant alignment along with soft tissue balance plays a vital role in the outcomes after total knee arthroplasty (TKA). Computer navigation for TKA was first introduced in 1997 with the aim of implanting the prosthetic components with accuracy and precision. This review discusses the technique, current status, and scientific evidence pertaining to computer-navigated TKA.

Body

The adoption of navigated TKA has slowly but steadily increased across the globe since its inception 25 years ago. It has been more rapid in some countries like Australia than others, like the UK. Contemporary, large console-based navigation systems help control almost every aspect of TKA, including the depth and orientation of femoral and tibial resections, soft-tissue release, and customization of femoral and tibial implant positions in order to obtain desired alignment and balance. Navigated TKA results in better limb and implant alignment and reduces outliers as compared to conventional TKA. However, controversy still exists over whether improved alignment provides superior function and longevity. Surgeons may also be hesitant to adopt this technology due to the associated learning curve, slightly increased surgical time, fear of pin site complications, and the initial set-up cost. Furthermore, the recent advent of robotic-assisted TKA which provides benefits like precision in bone resections and avoiding soft-tissue damage due to uncontrolled sawing, in addition to those of computer navigation, might be responsible for the latter technology taking a backseat.

Conclusion

This review summarizes the current state of computer-navigated TKA. The superiority of computer navigation to conventional TKA in improving accuracy is well established. Robotic-assisted TKA provides enhanced functionality as compared to computer navigation but is significantly more expensive. Whether robotic-assisted TKA offers any substantive advantages over navigation is yet to be conclusively proven. Irrespective of the form, the use of computer-assisted TKA is on the rise worldwide and is here to stay.

Trends of Utilization and 90-Day Complication Rates for Computer-Assisted Navigation and Robotic Assistance for Total Knee Arthroplasty in the United States From 2010 to 2018

Background

Computer-assisted navigation (CAN) and robotic assistance (RA) for total knee arthroplasty (TKA) are gaining in popularity. The purpose of this study is to update the literature on United States technology-assisted TKA trends of national utilization, regional utilization, and 90-day complication rates requiring readmission.

Methods

Patients who underwent primary, elective TKA between 2010 and 2018 were retrospectively identified in the PearlDiver All Payer Claims Database (PearlDiver Technologies Inc.). TKAs were classified as conventional, CAN, or RA based on International Classification of Diseases nineth or tenth revision and Current Procedural Technology codes. Annual rates and regional trends of each type of TKA were reported. Ninety-day complications requiring readmission for each group were captured. Multivariable logistic regression was used to identify odds ratios (OR) for all-cause readmission based on TKA modality.

Results

Of the 1,307,411 elective TKAs performed from 2010 to 2018, 92.8% were conventional, and 7.7% were technology-assisted (95.2% CAN and 4.9% RA). RA-TKA had the greatest increase in utilization (+2204%). The Western region had the highest utilization of technologies for TKA, while the Midwestern region had the lowest. Ninety-day postoperative complications requiring readmission were highest for conventional TKA and lowest for RA-TKA. RA-TKA (OR 0.68; 97.5% confidence interval 0.56-0.83, P < .001) and CAN-TKA (OR 0.93; 97.5% confidence interval 0.88-0.97, P < .05) had significantly lower odds of all-cause 90-day complications requiring readmission than conventional TKA.

Conclusion

Utilization of RA-TKA and CAN-TKA continues to rise across the United States. The use of these technologies is associated with a lower OR of readmission within 90 days postoperatively.

Complex joint-preserving bone tumor resection and reconstruction using computer navigation and 3D-printed patient-specific guides: A technical note of three cases

In selected extremity bone sarcomas, joint-preserving surgery retains the natural joints and nearby ligaments with a better function than in traditional joint-sacrificing surgery. Geometric multiplanar osteotomies around bone sarcomas were reported with the advantage of preserving more host bone. However, the complex surgical planning translation to the operating room is challenging.

Using both Computer Navigation and Patient-Specific Guide may combine each technique's key advantage in assisting complex bone tumor resections. Computer Navigation provides the visual image feedback of the pathological information and validates the correct placement of Patient-Specific Guide that enables accurate, guided bone resections. We first described the digital workflow and the use of both computer navigation and patient-specific guides (NAVIG) to assist the multiplanar osteotomies in three extremity bone sarcoma patients who underwent joint-preserving bone tumor resections and reconstruction with patient-specific implants. The NAVIG technique verified the correct placement of patient-specific guides that enabled precise osteotomies and well-fitted patient-specific implants. The mean maximum deviation errors of the nine achieved bone resections were 1.64 ​± ​0.35 ​mm (95% CI 1.29 to 1.99). The histological examination of the tumor specimens showed negative resection margin. At the mean follow-up of 55 months (40–67), no local recurrence was noted. There was no implant loosening that needed revision. The mean MSTS score was 29 (28–30) out of 30 with the mean knee flexion of 140° (130°–150°).

The excellent surgical accuracy and limb function suggested that the NAVIG technique might replicate the surgical planning of complex bone sarcoma resections by combining the strength of both Computer Navigation and Patient-Specific Guide. The patient-specific approach may translate into clinical benefits. The translational potential of this article:

The newly described technique enhances surgeons’ capability in performing complex joint-preserving surgery in bone sarcoma that is difficult to be achieved by the traditional method. The high precision and accuracy may translate into superior clinical outcomes.

False malalignment after computer-navigated total knee arthroplasty

BACKGROUND

Although computer navigation has improved component alignment in total knee arthroplasty (TKA), radiographic outliers are reported with a wide range in literature even using this technique. We hypothesized that the postoperative malalignment after computer-navigated TKA was partially derived from the inherent problems with two-dimensional (2D) measurement such as inaccuracies in measurement due to the knee position during the radiographic examination and the direction of the X-ray beam. We therefore conducted this study to determine how often knees with malalignment on 2D imaging were truly mal-aligned on three-dimensional (3D) reconstructed imaging.

METHODS

Sixty-two computer-navigated primary TKAs performed in 47 patients were included in this study. In all cases, a weight-bearing long-leg radiograph was obtained after TKA. 3D measurements were performed for outliers 2° or more in coronal alignment of the femoral or tibial component.

RESULTS

For the 18 femoral mal-aligned components on 2D imaging, eight (44.4%) were not truly mal-aligned on 3D imaging (P = 0.0014). For the eight tibial mal-aligned components on 2D imaging, all knees (100%) were not truly mal-aligned on 3D imaging (P < 0.0001).

CONCLUSIONS

A considerable number of the false malalignments were included on 2D measurement. Postoperative component alignment in the computer-navigated TKA might be much better than previously reported.

Bilateral Total Hip Arthroplasty in the Setting of Developmental Dysplasia of the Hip and Extreme Hip Flexion Requirements due to Phocomelia

Phocomelia is a rare congenital birth defect marked by hypoplastic or markedly absent limbs. Developmental dysplasia of the hip (DDH) is a congenital disorder with a failure of the native acetabulum to provide complete coverage over the femoral head. The secondary osteoarthritis that develops from DDH is technically challenging for orthopedic surgeons because of distorted anatomy. The present case describes the diagnosis of Crowe 3 DDH in a phocomelia patient with hyperflexion requirements who successfully underwent staged bilateral total hip arthroplasty via a direct anterior approach. It highlights the utility of preoperative computerized tomography and intraoperative computer navigation to assist in implant placement. Recognizing difficult arthroplasty cases in advance is imperative as these cases may require great expertise and more extensive surgical planning.

Knee Prosthesis in the Computer Era

Over the past two decades, computer assistance has revolutionalized surgery and has enabled enormous advancements in knee prosthesis surgery. Total knee arthroplasty (TKA) is a hot topic of orthopaedic research. Reflecting population dynamics, its use continues to increase, especially in high demand populations. Therefore, efforts to achieve the best fit and precise alignment in TKA continue. Computer assistance is valuable for knee prosthesis surgeons in this regard. This manuscript investigated the use of computer assistance in knee prosthesis surgery. The effects of computer use on important facets of knee prosthesis surgery, such as precision, clinical aspects, and costs, were examined. Moreover, an overall review of the recent literature on the navigation and personalized cutting guides was conducted.

Intraoperative navigation and preoperative templating software are associated with increased glenoid baseplate screw length and use of augmented baseplates in reverse total shoulder arthroplasty

Background

Preoperative templating software and intraoperative navigation have the potential to impact baseplate augmentation utilization and increase screw length for baseplate fixation in reverse total shoulder arthroplasty (rTSA). We aimed to assess their impact on the (1) baseplate screw length, (2) number of screws used, and (3) frequency of augmented baseplate use in navigated rTSA.

Methods

We compared 51 patients who underwent navigated rTSA with 63 controls who underwent conventional rTSA at a single institution. Primary outcomes included the screw length, composite screw length, number of screws used, percentage of patients in whom 2 screws in total were used, and use of augmented baseplates.

Results

Navigation resulted in the use of significantly longer individual screws (36.7 mm vs. 30 mm, P < .0001), greater composite screw length (84 mm vs. 76 mm, P = .048), and fewer screws (2.5 ± 0.7 vs. 2.8 ± 1, P = .047), as well as an increased frequency of using 2 screws in total (35 of 51 patients [68.6%] vs. 32 of 63 controls [50.8%], P = .047). Preoperative templating resulted in more frequent augmented baseplate utilization (76.5% vs. 19.1%, P < .0001).

Conclusion

The difference in the screw length, number of screws used, and augmented baseplate use demonstrates the evolving role that computer navigation and preoperative templating play in surgical planning and the intraoperative technique for rTSA.

Retained pelvic pin site debris after navigated total hip replacement: Masquerading as an early-stage chondrosarcomatous lesion

Once purely the domain of knee surgery, the use of computer-navigated techniques in total hip arthroplasty (THA) is becoming progressively more commonplace. As with the adoption of any new technology-assisted approach, the uptake of navigated THA utilization has heralded a new suite of technique-specific potential complications. One such example – not usually seen with conventional instrumented THA – pertains to complications related to the insertion and use of fixed pelvic array trackers. This case report describes the unusual circumstance of retained local bony debris generated through application of self-drilling, self-tapping iliac crest pins (for rigid navigation tracker placement) being mis-interpreted on advanced imaging - at a hospital site remote from the index surgery - as an aggressive, early-stage, chondrosarcomatous lesion. This case highlights the critical importance of both a general awareness of common imaging findings after navigated THA surgery (whereby tracker pins have been employed) and the value of 'hands on' clinical assessment of patients to allow correlation with suspicious imaging findings.

Artificial intelligence and surgical innovation: lower limb arthroplasty

The number of patients requiring hip and knee arthroplasty continues to rise each year. Patients are living longer and expecting to remain active into later life following joint replacement. Developments in computer-assisted surgery and robotic technology may optimise surgical outcomes and patient satisfaction following lower limb arthroplasty. The use of artificial intelligence in healthcare is rapidly growing and has gained momentum in lower limb arthroplasty. This article reviews the use of artificial intelligence and surgical innovation in lower limb arthroplasty, with a particular focus on robotic-assisted surgery in total knee arthroplasty.

Accelerometer-Based, Computer-Navigated Total Knee Arthroplasty to Correct a Complex Deformity in a Patient With Multiple Hereditary Exostoses

Background

Accelerometer-based computer-assisted navigation systems (ABCANSs) have been shown to improve alignment accuracy in total knee arthroplasty (TKA) and are effective in treating complex extra-articular deformity. We present an ABCANS-assisted TKA performed in a 68-year-old male with end-stage arthritis of the right knee, in the setting of a severe valgus deformity secondary to multiple hereditary exostoses.

Methods

The KneeAlign 2 system (OrthAlign, Inc.; Aliso Viejo, CA) was used to perform the TKA in this clinical scenario, given its functionality, which allows angular correction to be tailored to a given deformity, and its reported accuracy in performance of bony resection in TKA. The patient was prospectively followed up for one year postoperatively. Radiographs, PROMs, and patient satisfaction were reported.

Results

After the ABCANS-assisted TKA, the patient's alignment was improved from 25° to 4° of valgus. His final range of motion was 0-135° without an instability. In addition, the patient reported excellent scores on multiple joint-specific outcome measures, including the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the Forgotten Joint Score, and the Oxford Knee Score.

Conclusion

This case report illustrates the rationale, technique, and the excellent clinical outcomes achieved in a complex patient with extra-articular deformity using an ABCANS-assisted TKA.

Computer navigation assisted tumor surgery for internal hemipelvectomy - Early experience

Internal hemipelvectomy is a surgically challenging entity, owing, among other reasons, to a complex anatomy. The apprehension of an inadequate margin or injury to critical structures adds to the complexity of these major surgical procedures. Computer assisted tumor surgery (CATS) has been increasingly used to improve outcomes of internal hemipelvectomy over the last decade. We analyzed the surgical and postoperative details of first four patients undergoing internal hemipelvectomy with CATS assistance at our institute, the first ever report in an Indian setting. The patients were analyzed for blood loss (mean 1300 ml), operative time (mean 306 min) and hospital stay (mean 7 days). The histopathological margins were free of disease in all the patients, even as the average closest bony margin was 0.9 cm. Sparing of sacral nerve root was made possible by the close yet free margins in two patients. In this retrospective analysis of a small series of patients with computer navigation assisted internal hemipelvectomy, we found this technique to be feasible and effective in achieving the oncological aim of negative margins with preservation of critical structures.

A case-control study of computer navigation assisted resection of primary sacral chordoma above sacrum 3 level

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This is a retrospective case-control study.

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The computer navigation aided technology can make more cases achieve safe surgical margin.

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The clear bone resection margins were achieved in all cases in navigation group.

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The application of computer navigation doesn’t increase the operation time and intraoperative blood loss.

Background

The operation of sacral chordoma resection is difficult especial in the tumor above sacrum 3 level and the local recurrence rate was high. The purpose of this study is to analyze the effect of computer navigation aided technology in primary sacral chordoma resection above sacrum 3 level through a case-control study, which including perioperative safety, surgical margin, postoperative recurrence and function results.

Methods

This is a retrospective case-control study. The clinical data of 25 patients received initial computer-assisted resection of sacral chordoma above the level of sacrum 3 from 2009 to 2016 were analyzed; the patients underwent non-navigation assisted resection of tumor above the level of sacrum 3 in the same period were matched and 25 patients were selected randomly. There was no significant difference between these two groups in gender (P = 0.370), age (P = 0.554), tumor transverse diameter (P = 0.836). The average maximum diameter of tumor in navigation group was significant bigger than that in non-navigation group (P = 0.005). The intraoperative safety results, surgical margin, postoperative complications, recurrence rate and function were compared between these groups.

Results

There was no significant difference between navigation and non-navigation group in operative time (P = 0.105) and intraoperative blood loss (P = 0.537). There were 18 wide resections, 4 marginal resections and 3 intracapsular resections in navigation group; there were 6 wide resections, 12 marginal resections and 7 intracapsular resections in non-navigation group; the surgical margins of two groups were significant different (P = 0.003). There were 5 cases (20%) and 6 cases (24%) with wound complication in navigation group and non-navigation group (P = 0.733). The average follow-up was 49.6 (16–102) months in navigation group and 51.3 (12–110) months in non-navigation group. Three cases (12%) showed recurrence in navigation group and six cases showed recurrence (24%) in non-navigation group. The surgical margin was significantly related with tumor recurrence (P = 0.000). The average MSTS score was 27.3 (19–30) and 26.5 (20–29) in navigation group and non-navigation group (P = 0.374).

Conclusion

The computer navigation aided technology can improve the accuracy of primary sacral chordoma resection, and make more cases achieve safe surgical margin. Compared with the traditional operation, the application of computer navigation in the larger tumor resection does not increase the operation time and intraoperative blood loss, which shows good safety.

Computer navigation-assisted minimally invasive percutaneous screw placement for pelvic fractures

Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability. Traditional open surgery has a large amount of bleeding, which is not suitable for patients with acute pelvic fracture. Navigation-guided, percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages, which include less trauma, faster recovery times, and less bleeding. However, due to the complexity of pelvic anatomy, doctors often encounter some problems when using navigation to treat pelvic fractures. This article reviews the indications, contraindications, surgical procedures, and related complications of this procedure for the treatment of sacral fractures, sacroiliac joint injuries, pelvic ring injuries, and acetabular fractures. We also analyze the causes of inaccurate screw placement. Percutaneous screw placement under navigational guidance has the advantages of high accuracy, low incidence of complications and small soft-tissue damage, minimal blood loss, short hospital stays, and quick recovery. There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones. However, computer navigation technology requires extensive training, and attention should be given to avoid complications such as screw misplacement, intestinal injury, and serious blood vessel and nerve injuries caused by navigational drift.

Computer Navigation-Assisted Knee Replacement Demonstrates Improved Outcome Compared with Conventional Knee Replacement at Mid-Term Follow-up: A Systematic Review and Meta-analysis

The study is a systematic review and meta-analysis of prospective randomised control studies and prospective cohort studies of mid-term functional outcome of total knee replacement undertaken using imageless computer navigation compared with conventional instrumented total knee replacement. The literature search strategy included a search of the electronic databases, visual scanning of reference lists, hand searching of key journals and conference proceedings, and abstracts, citations, and trial registers. In total, 440 papers were retrieved after removal of duplicates, and with further screening, 11 papers were included in the systematic review and 6 papers were considered appropriate for meta-analysis. Analysis of the data showed evidence of a modest improvement in functional outcome at mid-term follow-up with use of imageless computer navigation assistance compared with conventional instrumented total knee replacement with a total score point estimate of 3.36 confidence interval (CI) (- 0.583, 7.298), objective score point estimate of 1.45 CI (0.11, 2.799), and functional score point estimate of 2.4, CI (- 1.174, 5.977). The predominant risk of bias was from random allocation and attrition. There is evidence of a modest improvement in functional outcome with the use of imageless computer navigation assistance compared with conventional instrumented total knee replacement at mid-term follow-up.

Optimal Flexion for the Femoral Component in TKR: A Study of Angle Between Mechanical Axis and Distal Anatomic Intramedullary Axis Using 3D Reconstructed CT Scans in 407 Osteoarthritic Knees Studied in India

BACKGROUND

The femoral component is generally aligned perpendicularly to the distal femoral intramedullary axis with conventional instruments. Various aids like computer navigation, patient-specific instrumentation and robotic surgery use the mechanical axis as the reference for the femoral component alignment. We studied the flexion of the distal femoral intramedullary axis compared to the mechanical axis using an interactive 3D tool in 407 Indian osteoarthritic knees undergoing total knee replacement to better understand optimal flexion alignment.

MATERIALS AND METHODS

407 knees (301-Female, 106-Male) in Indian patients undergoing total knee replacement underwent CT scans. A 3D interactive knee system was used for 3D reconstruction and planning. Distal femoral flexion angle (DFFA) was calculated between the anatomic distal femoral (intramedullary) axis and the mechanical axis. Statistical analysis was performed using ANOVA test and Chi-square test using a data analysis tool pack (Analysis ToolPak by Excel Easy) additionally installed in Microsoft Excel 2010.

RESULTS

The mean DFFA was found to be 2.54 with a standard deviation of 1.38. The maximum and minimum values noted were 7.5 and 0.5 respectively. There was no correlation found between sex, age, height or weight (p > 0.05).

CONCLUSIONS

While taking the distal femur cut with systems other than an intramedullary rod, in Indian osteoarthritic knees, it would be safer to take the distal femoral cut between 2 and 3 degrees of flexion to mechanical axis, as it would ensure that the cut is within 3 degrees from the anatomic axis for 98% patients. Most surgeons routinely using navigation or similar aids take the cut at 0 degrees of flexion to the mechanical axis. This will lead to more than 3 degrees of extension with reference to the intramedullary axis in more than 39% patients. This would result in either an increase in femoral component sizing or an increased risk of notching.

Accuracy of computer navigation in total knee arthroplasty: A prospective computed tomography-based study

INTRODUCTION

Evidence now exists advocating the use of computer navigation in total knee arthroplasty (TKA). Despite the introduction of new navigation systems into clinical practice no evidence currently exists showing independent verification of their accuracy. The aim of this study was to validate the in vivo accuracy of the Exactech Guided Personalised Surgery (GPS) computer navigation system using a validated computed tomography (CT) measurement of alignment.

METHOD

Consecutive patients who underwent TKA using the GPS Navigation System at our institution were prospectively recruited. Intraoperative parameters of 3D alignment as measured by the GPS navigation system were recorded and compared against the postoperative measurements of alignment measured using the Perth CT Protocol to assess the accuracy of the GPS navigation system.

RESULTS

29 consecutive patients (13 male, 16 female) who underwent TKA were prospectively recruited. Overall, for all measures of 3D alignment the mean difference between intraoperatively recorded and postoperative CT-measured alignment was 1.55° ± 0.22° (95% confidence interval). Individual measurement differences in the femoral prosthesis were: coronal alignment 1.64° ± 0.52°; flexion 2.07° ± 0.55°; rotation 1.38° ± 0.33° Differences in the tibial prosthesis were: coronal alignment 2.03° ± 0.53°; slope 1.14° ± 0.39° The whole limb coronal alignment difference was 2.34° ± 0.83° CONCLUSION: The Exactech GPS Navigation system is very accurate with a high concordance between intraoperative and postoperative measures of alignment and prosthesis positioning. We therefore confidently validate the system and support its continued use in clinical practice. Other navigation systems should undergo a similar validation process.

Clinical and radiographic outcomes of computer-navigated total knee arthroplasty are not adversely affected by body mass index

Aim

To study the effect of obesity on clinical and radiographic outcomes of computer-navigated knee arthroplasty.

Materials and methods

117 patients underwent primary computer-navigated total knee arthroplasty. Eight were lost to follow-up and 8 had incomplete data.

Results

Eighty-four (83.2%) female, 17 (16.8%) male patients age 65.3 ± 6.9 years with a pre-operative BMI 27.2 ± 4.1 (18.6-40.0) kg/m², 7.3 ± 0.98 years follow-up. Forty-two (41.6%) had a BMI>27.5 kg/m² indicative of obesity in Singapore. Post-operative radiographic alignment, 2-year Oxford knee scores and ROM were not significantly associated with BMI.

Conclusion

BMI is not a determinant of functional scores when computer navigation is used.

Technical and surgical causes of outliers after computer navigated total knee arthroplasty

Background

Navigated total knee arthroplasty (TKA) improves implant and limb alignment but outliers continue to exist. This study aimed to determine the technical and surgical causes of outliers.

Methods

This retrospective cohort study included 208 patients who had undergone navigated TKA. Limb and implant alignment indices were measured on post-operative CT scans: mechanical femoro-tibial angle (MFTA); coronal femoral angle (CFA); coronal tibial angle (CTA); sagittal femoral angle (SFA); and sagittal tibial angle (STA). Values outside 0°±3° for MFTA and SFA, 90°±3° for CFA, CTA and STA were considered outliers. Intra-operative navigation data and CT scans were evaluated to categorize the causes of sagittal and coronal plane outliers into hip centre error; ankle centre error; heterogeneous tibial cement mantle; malalignment accepted by surgeon; suboptimal knee balance; and no obvious explanation.

Results

Of the 1040 measurements (five per TKA), the overall incidence of outliers was 10.4% (n = 108). Femoral component outliers (CFA + SFA, n = 51) were all attributable to hip centre error. Tibial component outliers (CTA + STA, n = 43) were attributable to ankle centre error (n = 6), heterogeneous cement mantle (n = 20), malalignment accepted by the surgeon (n = 6) and no obvious cause (n = 11). MFTA outliers were attributable to hip centre error (n = 4) or suboptimal knee balance (n = 10).

Conclusions

Surgeon related errors can be minimized by a meticulous operative technique. These results indicate scope for additional technical improvement, especially in hip centre acquisition, which may further reduce the incidence of outliers.

Total knee arthroplasty in a case of diffuse idiopathic skeletal hyperostosis; challenges in ligament balancing and deformity correction

Introduction:

Diffuse skeletal idiopathic hyperostosis is a non-inflammatory systemic skeletal condition in which there is ossification of ligaments, tendons, and joint capsule. Although the radiological changes and clinical manifestation of diffuse idiopathic skeletal hyperostosis (DISH) in the spine have been well defined in the literature, the changes in the knee and their implications on knee replacement are unclear.

Case Report:

A 60 year -year-old patient presented with pain, stiffness, and decreased arc of movement at the right knee. The X-rays showed ossification of the joint capsule, ligaments, and quadriceps expansion. The spine had has calcification of the anterior longitudinal ligament and ‘“wax drop’ drop” enthesophytes. Based on the complete skeletal survey, a diagnosis of DISH was made. During knee arthroplasty, it was difficult to correct the deformity with a measured resection technique. Additional resection of 4 mm was done both from the distal femur and proximal tibia to correct the deformity and achieve optimal kinematics. This unpliable nature of the soft tissues due to enthesitis ossification of periarticular tissues led to decrease flexion postoperatively.

Conclusion:

Surgeons should keep the diagnosis of DISH in mind when dealing with a stiff knee and be prepared for additional bone resection with extensive soft tissue release to balance the prosthetic knee joint.

Kinematic alignment in total knee arthroplasty leads to a better restoration of patellar kinematics compared to mechanic alignment

PURPOSE

The influence of different implantation techniques in TKA on tibiofemoral kinematics was analysed in few investigations so far. However, the influence on patellar kinematics remain unclear. The aim of the present investigation was to compare patellar kinematics of the natural knee with those of knees after both kinematically and mechanically aligned TKAs.

METHODS

Patellar kinematics of ten cadaveric knees before and after TKAs implanted using both a kinematic and mechanic alignment technique were investigated and compared using a commercial optical computer navigation system.

RESULTS

There was a statistically significant difference between natural patellar kinematics and both implantation techniques analysing mediolateral shift. Patellar lateral tilt showed significant better results in the kinematically compared to the mechanically aligned TKAs. In terms of patella rotation, the patella of both mechanically and kinematically aligned TKAs showed significant higher values for external rotation compared to the natural knee. Regarding epicondylar distance again a significant better restoration of natural kinematics could be found in the kinematically aligned TKAs.

CONCLUSION

Kinematically aligned TKAs showed a better overall restoration of patellar kinematics compared to a conventional mechanical alignment technique. In terms of clinical usefulness, the present study highlights the potential benefit for clinical outcome using a kinematically aligned implantation technique in TKA to achieve a better restoration of natural patellofemoral kinematics.

Trends in computer navigation and robotic assistance for total knee arthroplasty in the United States: an analysis of patient and hospital factors

Background

Computer navigation and robotic assistance technologies are used to improve the accuracy of component positioning in total knee arthroplasty (TKA), with the goal of improving function and optimizing implant longevity. The purpose of this study was to analyze trends in the use of technology-assisted TKA, identify factors associated with the use of these technologies, and describe potential drivers of cost.

Methods

The Nationwide Inpatient Sample database was used to identify patients who underwent TKA using conventional instrumentation, computer navigation, and robot-assisted techniques between 2005 and 2014. Variables analyzed include patient demographics, hospital and payer types, and hospital charges. Descriptive statistics were used to describe trends. Univariate and multivariate analyses were performed to identify differences between conventional and technology-assisted groups.

Results

Our analysis identified 6,060,901 patients who underwent TKA from 2005 to 2014, of which 273,922 (4.5%) used computer navigation and 24,084 (0.4%) used robotic assistance. The proportion of technology-assisted TKAs steadily increased over the study period, from 1.2% in 2005 to 7.0% in 2014. Computer navigation increased in use from 1.2% in 2005 to 6.3% in 2014. Computer navigation was more likely to be used in the Western United States, whereas robot-assisted TKAs were more likely to be performed in the Northeast. Increased hospital charges were associated with the use of technology assistance ($53,740.1 vs $47,639.2).

Conclusions

The use of computer navigation and robot-assisted TKA steadily increased over the study period, accounting for 7.0% of TKAs performed in the United States in 2014. Marked regional differences in the use of these technologies were identified. The use of these technologies was associated with increased hospital charges.

Safety and Efficacy of Intraoperative Computer-Navigated Versus Non-Navigated Shoulder Arthroplasty at a Tertiary Referral

Emerging technologies in shoulder arthroplasty, such as 3-dimensional planning software and real-time intraoperative navigation, are now available for surgeons to perform more accurate placement of the glenoid component without malposition or perforation. Using these tools, the surgeon can visualize the version, inclination, and containment of the implant and determine whether augmented components would be necessary. This review provides an updated investigation of the present literature to elucidate the role of computer navigation in modern shoulder arthroplasty.

Computer navigation for total knee arthroplasty achieves better postoperative alignment compared to conventional and patient-specific instrumentation in a low-volume setting

BACKGROUND

Procedure volume is an important determinant of total knee arthroplasty (TKA) outcomes. We aimed to determine whether computer navigation or patient-specific instrumentation (PSI) would improve postoperative alignment in a low-volume setting.

HYPOTHESIS

PSI for TKA achieves better limb and implant alignment compared to conventional TKA and to computer navigated TKA.

MATERIALS AND METHODS

This is a retrospective cohort study of 385 primary TKAs (Women=59%. Mean age=67years. Mean BMI=30.1kg/m²), which were performed using conventional instrumentation (n=117; 30%), computer navigation (n=209; 54%), or patient-specific instrumentation (n=59; 15%) in a low-volume center (<50 TKAs/year). The risk of postoperative leg and implant mechanical alignment outliers in the coronal plane (>3° from neutral), average alignment and operation time were assessed.

RESULTS

The risk of postoperative mechanical alignment outliers (>3°) was reduced by 89% in the navigated group (4% outliers) compared to the conventional group (35%) (RR=0.11; p<0.0001). No significant improvement was observed in the PSI group (27%) (RR=0.91; p=0.772). The risk of postoperative femoral component coronal alignment outliers was reduced by 63% in the navigated group (11%) compared to the conventional group (31%) (RR=0.37; p=0.018). No significant reduction in outliers was observed in the PSI group (32%) (RR=1.08; p=0.816). There was a reduction in the risk of tibial component coronal malalignment of 66% in the navigated group (5%) compared to the conventional group (13%) (RR=0.33; p=0.070). There was a two-fold increase in the risk of tibial component alignment outliers in the PSI group (29%) (RR=1.94; p=0.110).

DISCUSSION

Computer navigation improved postoperative alignment in TKA. No evidence of improved alignment was seen with patient-specific instrumentation. The routine use of patient-specific instrumentation in low-volume centers is not supported by the currently available data.

TYPE OF STUDY

Retrospective cohort study. Level IV.

Toward a higher accuracy in orthognathic surgery by using intraoperative computer navigation, 3D surgical guides, and/or customized osteosynthesis plates: A systematic review

The aim of this study was to systematically review the accuracy of intraoperative computer navigation, three-dimensional surgical guides and customized osteosynthesis plates for the transfer of the virtual surgical plan to the patient in orthognathic surgery. A systematic review of the currently available publications was performed in databases MEDLINE, Embase, and Cochrane Library, using a PICOS search strategy, and reported according to PRISMA. The initial search yielded 3050 articles. In total, 16 studies were included for final quantitative analyses. The results of individual studies demonstrated a comparable accuracy in the transfer of planned surgical displacement of the jaws. A large variability was found with regard to the method of accuracy assessment and reported outcomes. The findings of this review show that these modern techniques have the potential to replace interocclusal splints in routine clinical practice in the future. We recommend that authors presenting new data on the accuracy of a technique should choose the method of accuracy assessment meticulously, acquiring postoperative imaging as soon as possible after surgery. They should report as much as possible, summarizing values or, ideally, even the raw data of the accuracy assessment in order to allow comparison with other techniques in a meta-analysis.

Long - term survivorship and clinical results of the navigated withdrawn ASR ™

Introduction

Primary goals of the study were to present the mid - to long - term survivorship and clinical, radiological and metal serological results of the first stem - navigated ASR™ resurfacing at our clinic. Secondary goals were to determine the influence of stem - navigation on the outcome and risk factors for revision in our cohort.

Methods

From Mai 2006 to Mai 2009 46 ASR™ resurfacing hip systems have been implanted in 43 patients with a median age of 55 years. At final follow - up (33 patients with a mean follow -up of 89,6 months) guidelines were followed and HHS and HOOS were completed. Inclination, NSA and SSA were measured on radiographs and signs of loosening were graded. Risk factors for revision were compared in the non - revision and revision group.

Results

Mean cumulative survival of the prosthesis after 99,9 Months was 81,8%. At final follow - up 8 revisions were performed. Median HHS was 97, HOOS was 87,2. Four prostheses showed signs of loosening and nine heterotopic ossifications. All shaft components, except one, were placed in minimal valgus position to avoid risk for fracture. Age and diameter of the femoral component were significantly different between the non - revision and revision group.

Discussion

Survivorship is comparable to numbers found in other studies. Patients with complete final follow - up in general had good objective and subjective scores and few signs of loosening in the radiological follow - up. Navigation might have a positive effect on reduction of risk for fracture. Age and diameter of the femoral component seem to influence the outcome.

Case-related factors affecting cutting errors of the proximal tibia in total knee arthroplasty assessed by computer navigation

PURPOSE

The aim of this study was to determine factors that contribute to bone cutting errors of conventional instrumentation for tibial resection in total knee arthroplasty (TKA) as assessed by an image-free navigation system. The hypothesis is that preoperative varus alignment is a significant contributory factor to tibial bone cutting errors.

METHODS

This was a prospective study of a consecutive series of 72 TKAs. The amount of the tibial first-cut errors with reference to the planned cutting plane in both coronal and sagittal planes was measured by an image-free computer navigation system. Multiple regression models were developed with the amount of tibial cutting error in the coronal and sagittal planes as dependent variables and sex, age, disease, height, body mass index, preoperative alignment, patellar height (Insall-Salvati ratio) and preoperative flexion angle as independent variables.

RESULTS

Multiple regression analysis showed that sex (male gender) (R = 0.25 p = 0.047) and preoperative varus alignment (R = 0.42, p = 0.001) were positively associated with varus tibial cutting errors in the coronal plane. In the sagittal plane, none of the independent variables was significant.

CONCLUSION

When performing TKA in varus deformity, careful confirmation of the bone cutting surface should be performed to avoid varus alignment. The results of this study suggest technical considerations that can help a surgeon achieve more accurate component placement.

LEVEL OF EVIDENCE

IV.

Stem cell therapy in bilateral osteonecrosis: computer-assisted surgery versus conventional fluoroscopic technique on the contralateral side

PURPOSE

Surgical management of osteonecrosis with core decompression with stem cell therapy is a new procedure. The technique is performed with fluoroscopic guidance. This study attempts to determine if computer-navigated technique can improve the procedure.

METHODS

Thirty consecutive patients with bilateral symptomatic osteonecrosis without collapse were included in this study during the year 2011. A prospective, randomized, and controlled study was conducted on 60 hips (bilateral osteonecrosis) using conventional fluoroscopy technique on one side and computer-based navigation on the contralateral side. Bone marrow aspirated from the two iliac crests was mixed before concentration. Each side received the same volume of concentrated bone marrow and the same number of cells 110,000 ± 27,000 cells (counted as CFU-F).

RESULTS

Computer navigation achieved better parallelism to the ideal position of the trocar, with better trocar placement as regards to tip-to-subchondral distance and ideal centre position within the osteonecrosis for injection of stem cells. Using computer navigation took fewer attempts to position the trocar, used less fluoroscopy time, and decreased the radiation exposure as compared with surgery performed with conventional fluoroscopy. At the most recent follow-up (6 years), increasing the precision with computer navigation resulted in less collapse (7 versus 1) and better volume of repair (13.4 versus 8.2 cm³) for hips treated with the computer-assisted technique.

CONCLUSIONS

The findings of this study suggest that computer navigation may be safely used in a basic procedure for injection of stem cells.

Columbus® computer navigated total knee arthroplasty: Gap balancing versus measured resection

BACKGROUND

The aim of this study was to compare the medium term functional outcome and patient satisfaction of gap balanced (GB) with measured resection (MR) total knee arthroplasty (TKA) using computer navigation.

METHODS

A cohort of 144 consecutive computer navigated TKA were retrospectively identified from an arthroplasty database. Functional assessment using the Oxford Knee Score (OKS) and patient satisfaction were obtained from 113 patients at a mean follow-up of 5.4 (range four to seven) years. There were 44 patients in the GB group and 69 patients in the MR group.

RESULTS

The mean OKS for the GB group was 36.9 (SD 9.2) and for the MR was 33.6 (SD 9.8), with a difference of 3.3 (95% CI 0.3 to 6.3) points, which was statistically significant (p=0.01). Linear regression analysis confirmed the independent effect of surgical technique when adjusting for confounding factors and surgeon, with the GB group achieving a greater post-operative OKS (R²=0.39, 3.0 points, 95% CI 1.2 to 4.8, p=0.001). There was a greater rate of patient satisfaction in the GB group (88.6%, n=39/44) compared to the MR group (81.1%, n=56/69), but this was not statistically significant (odds ratio 1.8, 95% CI 0.6 to 5.5, p=0.31).

CONCLUSION

Computer navigated Columbus® TKA using a GB technique results in a statistically significantly greater functional outcome but no significant difference in patient satisfaction in the medium term compared to patients undergoing a MR technique.

Patient-related factors influence stiffness of the soft tissue complex during intraoperative gap balancing in cruciate-retaining total knee arthroplasty

PURPOSE

How much force is needed to pre-tension the ligaments during total knee arthroplasty? The goal of this study was to determine this force for extension and flexion, and for both compartments, and to identify predicting patient-related factors.

METHODS

Eighty patients [55 females, mean age 71 (SD 9.7)] were recruited and had a navigated cruciate-retaining total knee arthroplasty. Distraction of the medial and lateral compartments of the extension and flexion gap (90°) with an instrumented bi-compartmental double-spring tensioner took place after finishing the bone cuts. Applied forces and resulting gap distances were recorded by the navigation system, resulting in a force-elongation curve. Lines were fitted with the intersection defined as the stiffness transition point. The slopes (N/mm) represented the stiffness of the ligamentous complex. Linear multiple regression analysis was performed to identify predicting factors.

RESULTS

The amount of force at the stiffness transition point was on average 52.3 (CI₉₅ 50.7-53.9), 54.5 (CI₉₅ 52.7-56.3), 48.3 (CI₉₅ 46.2-50.2), and 59.3 (CI₉₅ 57.0-61.6) N for the medial and lateral extension and flexion gap, respectively, and varied considerably between patients. The force at the stiffness transition point was significantly different between extension and flexion and both compartments (P < 0.05). Stiffness of the ligaments statistically significantly helped to predict the amount of force at the stiffness transition point, as well as body mass index, gender, and varus-valgus alignment.

CONCLUSION

The amount of force at the stiffness transition point varies between 48 and 59 N, depending on flexion/extension and compartment. Patient-related factors influence the stiffness transition point and can help predict the stiffness transition point. When forces higher than 60 N are used for gap distraction, the ligamentous sleeve of the knee might be over-tensioned.

LEVEL OF EVIDENCE

Prognostic study, Level I-high-quality prospective cohort study with >80 % follow-up, and all patients enrolled at same time point in disease.

Computer navigation-assisted surgery for musculoskeletal tumors: a closer look into the learning curve

BACKGROUND

Computer navigation-assisted surgery for musculoskeletal tumors has shown to reduce the risk of intra-lesional margins in resection. Experiences with this method are still limited to smaller case series.

METHOD

We reviewed our first experiences in 24 patients in whom computer navigation-assisted surgery had been performed. In 7 of these patients (6 male and 1 female), this has influenced the surgical treatment plan and navigation was used for both tumor resection and reconstruction. Three of the patients suffered from a chondrosarcoma, 2 from an osteosarcoma, 1 from a fibrosarcoma and 1 from an Ewing's sarcoma. Tumors were localized in the femur (n = 2), the tibia (n = 1), the sacrum (n = 1), the humerus (n = 1), the ilium (n = 1) and in the gluteal region (n = 1).

RESULTS

The mean registration error was 0.9 mm. No intra-operative complications occurred. Two postoperative complications were observed which required revision surgery. Except for one marginal resection, all tumors were excised with wide margins. One patient suffered from a local recurrence, and one patient died of disease after distant metastatic dissemination.

CONCLUSION

Computer navigation-assisted surgery represents a safe and helpful tool for the resection of musculoskeletal tumors and may influence surgical treatment plans in selected cases to provide more limited resections. Surgeons should be aware of risks considering biomechanical and oncological consequences in doing so. Further investigations and the evaluation of newer techniques (e.g., computed tomography-guided navigation) are needed to assess long-term outcomes of computer navigation assistance in musculoskeletal tumor surgery.

Postoperative alignment of TKA in patients with severe preoperative varus or valgus deformity: is there a difference between surgical techniques?

BACKGROUND

There have been conflicting studies published regarding the ability of various total knee arthroplasty (TKA) techniques to correct preoperative deformity. The purpose of this study was to compare the postoperative radiographic alignment in patients with severe preoperative coronal deformity (≥10° varus/valgus) who underwent three different TKA techniques; manual instrumentation (MAN), computer navigated instrumentation (NAV) and patient specific instrumentation (PSI).

METHODS

Patients, who received a TKA with a preoperative coronal deformity of ≥10° with available radiographs were included in this retrospective study. The groups were: MAN; n = 54, NAV; n = 52 and PSI; n = 53. The mechanical axis (varus / valgus) and the posterior tibial slope were measured and analysed using standing long leg- and lateral radiographs.

RESULTS

The overall mean postoperative varus / valgus deformity was 2.8° (range, 0 to 9.9; SD 2.3) and 2.5° (range, 0 to 14.7; SD 2.3), respectively. The overall outliers (>3°) represented 30.2% (48 /159) of cases and were distributed as followed: MAN group: 31.5%, NAV group: 34.6%, PSI group: 24.4%. No significant statistical differences were found between these groups. The distribution of the severe outliers (>5°) was 14.8% in the MAN group, 23% in the NAV group and 5.6% in the PSI group. The PSI group had significantly (p = 0.0108) fewer severe outliers compared to the NAV group while all other pairs were not statistically significant.

CONCLUSIONS

In severe varus / valgus deformity the three surgical techniques demonstrated similar postoperative radiographic alignment. However, in reducing severe outliers (> 5°) and in achieving the planned posterior tibial slope the PSI technique for TKA may be superior to computer navigation and the conventional technique. Further prospective studies are needed to determine which technique is the best regarding reducing outliers in patients with severe preoperative coronal deformity.

Conventional versus computer-navigated TKA: a prospective randomized study

PURPOSE

The purpose of this study was to assess the midterm results of total knee arthroplasty (TKA) implanted with a specific computer navigation system in a group of patients (NAV) and to assess the same prosthesis implanted with the conventional technique in another group (CON); we hypothesized that computer navigation surgery would improve implant alignment, functional scores and survival of the implant compared to the conventional technique.

METHODS

From 2008 to 2009, 225 patients were enrolled in the study and randomly assigned in CON and NAV groups; 240 consecutive mobile-bearing ultra-congruent score (Amplitude, Valence, France) TKAs were performed by a single surgeon, 117 using the conventional method and 123 using the computer-navigated approach. Clinical outcome assessment was based on the Knee Society Score (KSS), the Hospital for Special Surgery Knee Score and the Western Ontario Mac Master University Index score. Component survival was calculated by Kaplan-Meier analysis.

RESULTS

Median follow-up was 6.4 years (range 6-7 years). Two patients were lost to follow-up. No differences were seen between the two groups in age, sex, BMI and side of implantation. Three patients of CON group referred feelings of instability during walking, but clinical tests were all negative. NAV group showed statistical significant better KSS Score and wider ROM and fewer outliers from neutral mechanical axis, lateral distal femoral angle, medial proximal tibial angle and tibial slope in post-operative radiographic assessment. There was one case of early post-operative superficial infection (caused by Staph. Aureus) successfully treated with antibiotics. No mechanical loosening, mobile-bearing dislocation or patellofemoral complication was seen. At 7 years of follow-up, component survival in relation to the risk of aseptic loosening or other complications was 100 %. There were no implant revisions.

CONCLUSION

This study demonstrates superior accuracy in implant positioning and statistical significant better functional outcomes of computer-navigated TKA. Computer navigation for TKAs should be used routinely in primary implants.

LEVEL OF EVIDENCE

II.

Do CAS measurements correlate with EOS 3D alignment measurements in primary TKA?

PURPOSE

Objective of this study was to compare intraoperative computer-assisted surgery (CAS) alignment measurements during total knee arthroplasty (TKA) with pre- and postoperative coronal alignment measurements using EOS 3D reconstructions.

METHODS

In a prospective study, 56 TKAs using imageless CAS were performed and coronal alignment measurements were recorded twice: before bone cuts were made and after implantation of the prosthesis. Pre- and postoperative coronal alignment measurements were performed using EOS 3D reconstructions. Thanks to the EOS radiostereography system, measurement errors due to malpositioning and deformity during acquisition are eliminated. CAS measurements were compared with EOS 3D reconstructions. Varus/valgus angle (VV), mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured.

RESULTS

Significantly different VV angles were measured pre- and postoperatively with CAS compared to EOS. For preoperative measurements, mLDFA did not differ significantly, but a significantly larger mMPTA in valgus was measured with CAS.

CONCLUSION

Results of this study indicate that differences in alignment measurements between CAS measurements and pre- and postoperative EOS 3D are due mainly to the difference between weight-bearing and non-weight-bearing position and potential errors in validity and reliability of the CAS system. EOS 3D measurements overestimate VV angle in lower limbs with substantial mechanical axis deviation. For lower limbs with minor mechanical axis deviation as well as for mMPTA measurements, CAS measures more valgus than EOS. Eventually the results of this study are of clinical relevance, since it raises concerns regarding the validity and reliability of CAS systems in TKA.

LEVEL OF EVIDENCE

IIb.

Current state of computer navigation and robotics in unicompartmental and total knee arthroplasty: a systematic review with meta-analysis

Recently, there is a growing interest in surgical variables that are intraoperatively controlled by orthopaedic surgeons, including lower leg alignment, component positioning and soft tissues balancing. Since more tight control over these factors is associated with improved outcomes of unicompartmental knee arthroplasty and total knee arthroplasty (TKA), several computer navigation and robotic-assisted systems have been developed. Although mechanical axis accuracy and component positioning have been shown to improve with computer navigation, no superiority in functional outcomes has yet been shown. This could be explained by the fact that many differences exist between the number and type of surgical variables these systems control. Most systems control lower leg alignment and component positioning, while some in addition control soft tissue balancing. Finally, robotic-assisted systems have the additional advantage of improving surgical precision. A systematic search in PubMed, Embase and Cochrane Library resulted in 40 comparative studies and three registries on computer navigation reporting outcomes of 474,197 patients, and 21 basic science and clinical studies on robotic-assisted knee arthroplasty. Twenty-eight of these comparative computer navigation studies reported Knee Society Total scores in 3504 patients. Stratifying by type of surgical variables, no significant differences were noted in outcomes between surgery with computer-navigated TKA controlling for alignment and component positioning versus conventional TKA (p = 0.63). However, significantly better outcomes were noted following computer-navigated TKA that also controlled for soft tissue balancing versus conventional TKA (mean difference 4.84, 95 % Confidence Interval 1.61, 8.07, p = 0.003). A literature review of robotic systems showed that these systems can, similarly to computer navigation, reliably improve lower leg alignment, component positioning and soft tissues balancing. Furthermore, two studies comparing robotic-assisted with computer-navigated surgery reported superiority of robotic-assisted surgery in controlling these factors. Manually controlling all these surgical variables can be difficult for the orthopaedic surgeon. Findings in this study suggest that computer navigation or robotic assistance may help managing these multiple variables and could improve outcomes. Future studies assessing the role of soft tissue balancing in knee arthroplasty and long-term follow-up studies assessing the role of computer-navigated and robotic-assisted knee arthroplasty are needed.

Surgical accuracy in high tibial osteotomy: coronal equivalence of computer navigation and gap measurement

PURPOSE

Medial opening wedge high tibial osteotomy (MOW HTO) is now a successful operation with a range of indications, requiring an individualised approach to the choice of intended correction. This manuscript introduces the concept of surgical accuracy as the absolute deviation of the achieved correction from the intended correction, where small values represent greater accuracy. Surgical accuracy is compared in a randomised controlled trial (RCT) between gap measurement and computer navigation groups.

METHODS

This was a prospective RCT conducted over 3 years of 120 consecutive patients with varus malalignment and medial compartment osteoarthritis, who underwent MOW HTO. All procedures were planned with digital software. Patients were randomly assigned into gap measurement or computer navigation groups. Coronal plane alignment was judged using the mechanical tibiofemoral angle (mTFA), before and after surgery. Absolute (positive) values were calculated for surgical accuracy in each individual case.

RESULTS

There was no significant difference in the mean intended correction between groups. The achieved mTFA revealed a small under-correction in both groups. This was attributed to a failure to account for saw blade thickness (gap measurement) and over-compensation for weight bearing (computer navigation). Surgical accuracy was 1.7° ± 1.2° (gap measurement) compared to 2.1° ± 1.4° (computer navigation) without statistical significance. The difference in tibial slope increases of 2.7° ± 3.9° (gap measurement) and 2.1° ± 3.9° (computer navigation) had statistical significance (P < 0.001) but magnitude (0.6°) without clinical relevance.

CONCLUSION

Surgical accuracy as described here is a new way to judge achieved alignment following knee osteotomy for individual cases. This work is clinically relevant because coronal surgical accuracy was not superior in either group. Therefore, the increased expense and surgical time associated with navigated MOW HTO is not supported, because meticulously conducted gap measurement yields equivalent surgical accuracy.

LEVEL OF EVIDENCE

I.

Verification of in vivo accuracy of Trumatch™ patient-specific instrumentation in total knee replacement using pin-less computer navigation

PURPOSE

Accurate component alignment in total knee replacement (TKR) is one of the important factors in determining long-term survivorship. This has been achieved by conventional jigs, computer-assisted technology (CAS) and more recently patient-specific instrumentation (PSI). The purpose of the current study was to investigate the in vivo accuracy of Trumatch™ PSI using validated pin-less computer navigation system.

METHOD

Twenty consecutive selected patients that fulfilled our inclusion/exclusion criteria underwent TKR using PSI. Coronal alignment, posterior slope, resection thickness and femoral sagittal alignment were recorded using pin-less navigation. The position of the actual cutting block was appropriately adjusted prior to proceeding to definitive resections.

RESULTS

The coronal alignment using PSI without the assistance of navigation would have resulted in 14 (70 %) within ±3°, 11 (55 %) within ±2° and 6 (30 %) outside acceptable alignment. Thirty-five percentage of proposed femur sagittal alignment and 55 % of posterior tibial slope were achieved within ±3°. Components size was accurately predicted in 95 % of femurs and 90 % of tibia.

CONCLUSION

The purported advantages in restoring alignments using Trumatch™ PSI alone over standard equipment are debatable. However, it predicts sizing well, and femoral coronal alignment is reasonable. Combining Trumatch™ PSI with CAS will allow in vivo verification and necessary corrections.

LEVEL OF EVIDENCE

IV.

Significant influence of rotational limb alignment parameters on patellar kinematics: an in vitro study

PURPOSE

Component malrotation has a major impact on patellar kinematics in total knee arthroplasty. The influence of natural rotational limb alignment on patellar kinematics is unclear so far. Based on recent clinical investigations, we hypothesized that rotational limb alignment significantly influences patellar kinematics.

METHODS

Patellar kinematics of ten cadaveric knees was measured using computer navigation during passive motion. Data were correlated with different rotational limb alignment parameters of preoperative CT scans.

RESULTS

Femoral antetorsion showed a significant influence on patellar rotation, while tibial tubercle-posterior cruciate ligament distance additionally displayed a significant influence on patellar mediolateral shift (p < 0.05). Femoral posterior condylar angle was sensitive to patellar epicondylar distance, rotation and tilt (p < 0.05). Patellar rotation was influenced by five out of eight rotational limb alignment parameters (p < 0.05).

CONCLUSIONS

Rotational limb alignment should be paid more attention in terms of clinical evaluation of patellar tracking and future biomechanical and clinical investigations.

Preoperative planning for implant placement with consideration of pelvic tilt in total hip arthroplasty: postoperative efficacy evaluation

Background

In total hip arthroplasty (THA), tilting of the pelvis alters the cup placement angles. Thus, the cup angles need to be planned with consideration of the effects of pelvic tilt. In the present study, we evaluated the efficacy of preoperative planning for implant placement with consideration of pelvic tilt in THA, and the accuracy of a CT-based computer navigation for implant positioning.

Methods

We examined 75 hips of 75 patients who underwent THA and were followed-up for one year postoperatively. The patients were divided into three groups (anterior, intermediate, posterior tilt) according to their preoperative pelvic tilt. Preoperative planning for implant placement was made with consideration of pelvic tilt and a CT-based navigation was used to execute the preoperative planning. Cup inclination, cup anteversion, and combined anteversion (CA) in supine and standing positions were examined 1 year after THA. The accuracy of the computer navigation was also examined.

Results

Mean CA was 35.0 ± 5.8° in supine position and 39.3 ± 5.7° in standing position. CA did not differ among the three subgroups (anterior, intermediate, posterior tilt) in either supine or standing position, indicating implant placements to be equally effective. The desired CA (37.3°) was midway between those in supine and standing positions for each subgroup. Respective mean absolute errors between preoperative planning and postoperative CT measurement was 5.3 ± 5.2° for CA.

Conclusion

We obtained favorable THA results with preoperative planning with consideration of pelvic tilt by demonstrating supine and standing CA to be unaffected by preoperative pelvic tilt one year postoperatively. Mean absolute error of CA between preoperative planning and postoperative measurement was 5° with use of the CT-based navigation.

Open Surgery for Osteoid Osteoma with Three Dimensional C-arm Scan under the Guidance of Computer Navigation

OBJECTIVE

To evaluate the clinical outcomes of open surgery for osteoid osteoma with three-dimensional (3-D) C-arm scan under the guidance of computer navigation.

METHODS

The clinical data of 14 patients who had undergone 3-D C-arm scan under the guidance of computer navigation during open surgery for osteoid osteoma from March 2012 to June 2015 were analyzed retrospectively. There were nine male and five female subjects aged from 9 to 55 years (mean, 26 years). Eight of the tumors were located in the femur, four in the tibia, one in the humerus and one in the scapula. Preoperative pain visual analogue scale (VAS) scores ranged from 2 to 6 (mean ± SD, 4.7 ± 1.1). Conventional surgical approaches were used to expose the tumor surfaces depending on their locations. Involved regions were scanned by 3-D C-arm fluoroscopy during the procedure and then the tumors were accurately located and their niduses removed under the guidance of computer navigation. Afterwards, repeat 3-D C-arm scans of the surgical region were performed to confirm tumor eradication. None of the patients received postoperative intravenous analgesia. Eight patients received oral non-steroidal anti-inflammatory drugs on the day of surgery, these drugs being discontinued on the second postoperative day. Postoperative pathological diagnoses were recorded. At the follow-up visits, imaging and VAS scores were obtained to evaluate the therapeutic effect and any evidence of recurrence.

RESULTS

All the patients successfully underwent computer navigation-guided surgery. The duration of surgery ranged from 60 to 135 min (mean, 94 min) and the amount of bleeding from 50 to 150 mL (mean, 80 mL). None of the patients needed bone grafting or internal fixation. No complications were seen. All patients were followed up for 4 to 36 months (mean, 16 months). Postoperative pathological diagnoses of osteoid osteoma were made in 12 patients; thus, the rate of pathologically confirmed diagnosis was 86%. VAS scores decrease to an average of 1.4 ± 0.6 3 days after surgery and were zero for all patients 4 months after surgery. No tumor recurrence was found by X-ray or CT scan examination during follow-up.

CONCLUSIONS

The niduses of osteoid osteomas can be eradicated by open surgery with 3-D C-arm scan under the guidance of computer navigation with minimal damage to bone structure and a high rate of pathologically confirmed diagnoses.