Computer-assisted Total Knee Replacement Research Articles

Post-operative ankle complications after TKR: Could computer-assisted TKR solve the problem?

Post-operative ankle complications after TKR: Could computer-assisted TKR solve the problem?

Computer-Assisted TKR Vs Conventional TKR: Post-Operative Ankle Radiographic Finding and Ankle Clinical Assessment

Background: Few previous studies showed that the conventional total knee replacement (TKR) has affection to the same side of talar tilt (TT). We expected to prevent this problem by the computer-assisted (CAS) TKR. Objective: The purpose of this study was to compare between pre and post-operative talar tilt and ankle clinical assessment on the CAS TKR and the Conventional TKR in 28 patients (56 knees) whom underwent bilateral TKR. Material and Method: 28 patients, 56 knees, whom underwent both CAS total knee replacement (TKR) and conventional total knee replacement (TKR), in both knees, with the combination of Gap Balance and Measurement Resection techniques performed by one surgeon (P. Sriphirom) at Rajavithi Hospital, Bangkok. The post-operative has a 12 months follow-up for ankle radiographic finding by tibiotalar angle (TTA), tibial articular surface angle (TAS), and talar tilt (TT) = (TAS-TTA) and for ankle clinical assessment by foot functional index (FFI) from pre-operation and post-operation from both groups. The study also compares the CAS TKR with the Conventional TKR for pre-operation and post-operation. Results: 56 knees, 28 patients, mean age = 67.79 years whom underwent bilateral TKR by the Conventional group and the CAS group had pre-operative TT (TT = TAS - TTA). The Conventional group = 1.5 (-5, 8), the CAS group = .5 (-5, 8), P value = .65. On post-operative TT the Conventional group = .0 (-5, 3), the CAS group = 1.0 (-3, 8), the P value = .4. The comparison of pre-operative TT and post-operative TT in the Conventional group, the P value = .01. On pre-operative TT and post-operative TT in the CAS group, the P value = .65. TT was significantly different in the Conventional group but was not significantly different in the CAS group. The ankle clinical assessment by foot functional index (FFI), which is (1) Pain, (2) Difficulty living, and (3) Daily life activity limitation. The pre-operative FFI in the Conventional group = 1.85 (.81, 6.88) and pre-operative FFI in the CAS group = 1.91 (.24, 66.5), the P value = .57. The post-operative FFI in the Conventional group = 1.68 (0.24, 7.0) and post-operative FFI in the CAS group = 1.65 (.24, 6.76), the P value = .04, which showed a significantly different between the post-operative FFI from both groups. In the Conventional group the post-operative FFI was not significantly different from pre-operative FFI, the P value = .2 but for the CAS group the post-operative FFI was not significantly different from pre-operative FFI, the P value = .04. Conclusion: This study has shown that the conventional TKR effected to post-operative talar tilt but the CAS TKR has less effect and was not significantly different to ankle joint. Finally, the study needs to be conducted on more patients and to be observed on a longer term follow-up.

Jig Prototype for Computer-Assisted Total Knee Replacement and Its Flow Simulation

This paper discusses the design and development of a prototype of a knee surgery cutting jig, the jig holder, and the jig injection mold by Rapid Prototyping (RP). The aim of this study is to design a jig and a jig holder that allow surgeons to correctly, precisely, and consistently perform knee replacement surgery. The design concept for the surgery jig and jig holder was selected using the Pugh method with medical-grade 316L stainless steel for material fabrication. A rapid prototype model was built directly from its CAD model in stereo lithography (STL) format by using the Fused Deposition Method (FDM). MasterCAM and Moldflow simulation were performed to generated G-codes and a possibility of jig fabrication using Metal Injection Molding (MIM), respectively. The Moldflow result provided an enhanced interpretation of the injection mold design. A conceptual mold design was again developed by the FDM. The prototype of the cutting jig and its holder underwent a machining process. The prototype was then tested on dummy bones to determine the functional performance and efficiency of the said prototype. Results indicated an increase in cutting accuracy and cutting time compared with computer-assisted total knee surgery without the jig system.

Computer-assisted total knee replacement after medial opening wedge high tibial osteotomy: medium-term results in a series of ninety cases.

The aim of this study was to evaluate the medium-term results of total knee replacements (TKRs) after medial opening wedge valgising tibial osteotomy to those of primary TKR (TKR1). The hypothesis being that there would be no difference in results between these groups. Series 1 was made up of 45 TKRs after medial opening wedge high tibial osteotomy (MHTO)-30 men and ten women at an average age of 69 ± seven years (54-82). This was compared to a second series of TKR1s-30 men and ten women at an average age of 69 ± seven years (55-78). The average IKS scores were 91 ± 22.5 points (42-129) and 86 ± 18 points (38-116) in the two groups respectively. The average pre-operative HKA angle was 179 ± 5° (169-193°) in group 1, and 173 ± 7.5° (161-193°) in group 2. Tibial mechanical axes were 90.5 ± 4° (of which 24 knees had a valgus angle) and 85.05 ± 3.5° (79-93°) in the two groups respectively. All patients were reviewed at an average follow-up of 47 ± 24.5 months for series 1 and 185 ± 8.5 months for series 2. The average IKS score was 184 ± 6 for series 1 (172-200) and 185 ± 8.5 (163-200) for series 2 (p = 0.872). Thirty-seven patients in series 1 and 38 patients in series 2 were either extremely satisfied or satisfied with the intervention. The average post-operative HKA angle was 180.5 ± 2.5° and 181 ± 2° (p = 0.122) and the average tibial mechanical axis was 89 ± 1.5° against 90 ± 1° (p = 0.001). The results of the 24 knees with a valgus tibial mechanical axis were statistically no different. TKRs post medial opening wedge high tibial osteotomy have identical results to primary TKRs even in knees with a valgus tibial mechanical axis.

Minimal invasive and computer-assisted total knee replacement compared with the minimal invasive technique: a prospective, randomized trial with short-term outcomes

Up to now, no prospective, randomized comparisons between minimal invasive and computer-assisted total knee arthroplasty (MICA-TKA), and minimal invasive technique (MI-TKA) has been documented to evaluate not only clinical, but also radiologic results of the MICA-TKA. This prospective, randomized study was performed to compare the short-term results of MICA-TKA with minimal invasive technique MI-TKA for 6-month follow-up. We reported the clinical and radiological results of 80 subjects who had cruciate-substituting, TKA-implanted primary total knee arthroplasties using either minimal invasive and computer-assisted technique (40 patients Group I) or minimal invasive technique (40 patients, Group II). Tourniquet time, length of skin incision, and total blood loss were compared. Knee society scores (KSSs), knee society functional scores (KSFSs), range of motion (ROM), and radiographic results were assessed and reported preoperatively and at 6-month follow-up. The accuracy of the implantations in relation to the coronal mechanical axis in Group I was superior to that of Group II (P < 0.05). The femoral rotational profile revealed the prosthesis in Group I that was implanted with significantly less internal rotation than in Group II. The average blood loss in patients of Group I was significantly reduced as compared to patients of Group II. No significant difference was detected in terms of tourniquet time or length of skin incision. Clinical results, with regard to ROMs and KSSs, as well as KSFSs were equally good in both the groups. Better alignment and similarity of good clinical results at short-term follow-up may provide subjects who receive MICA-TKA with long-term endurance of their implants. Further studies on longer-term outcomes and functional improvements are required to validate these possibilities.

Is computer-assisted total knee replacement for beginners or experts? Prospective study among three groups of patients treated by surgeons with different levels of experience

BackgroundComputer-assisted total knee replacement (TKR) has been shown to improve radiographic alignment and therefore the clinical outcome. Outliers with greater than 3° of varus or valgus malalignment in TKR can suffer higher failure rates. The aim of this study was to determine the impact of experience with both computer navigation and knee replacement surgery on the frequency of errors in intraoperative bone cuts and implant alignment, as well as the actual learning curve.Materials and methodsThree homogeneous groups who underwent computer-assisted TKR were included in the study: group A [surgery performed by a surgeon experienced in both TKR and computer-assisted surgery (CAS)], B [surgery performed by a surgeon experienced in TKR but not CAS], and C [surgery performed by a general orthopedic surgeon]. In other words, all of the surgeons had different levels of experience in TKR and CAS, and each group was treated by only one of the surgeons. Cutting errors, number of re-cuts, complications, and mean surgical times were recorded. Frontal femoral component angle, frontal tibial component angle, hip–knee–ankle angle, and component slopes were evaluated.ResultsThe number of cutting errors varied significantly: the lowest number was recorded for TKR performed by the surgeon with experience in CAS. Superior results were achieved in relation to final mechanical axis alignment by the surgeon experienced in CAS compared to the other surgeons. However, the total number of outliers showed no statistically significant difference among the three surgeons. After 11 cases, there were no differences in the number of re-cuts between groups A and C, and after 9 cases there were no differences in surgical time between groups A and B.ConclusionA beginner can reproduce the results of an expert TKR surgeon by means of navigation (i.e., CAS) after a learning curve of 16 cases; this represents the break-even point after which no statistically significant difference is observed between the expert surgeon and the beginner utilizing CAS.

Post traumatic knee arthritis: Navigated total knee replacement without hardware removal

BackgroundThe Authors present the results of a series of navigated total knee replacements (TKR) without hardware removal in patients with post-traumatic arthritis following femoral fractures. The purpose of the paper was to determine the effectiveness of computer-assisted TKR in these patients compared to routine primary implants. MethodsSixteen patients with post-traumatic knee arthritis following a distal femoral fracture and retained hardware were included in the study (group I). Patients in the study group were matched with patients who had undergone a computer navigated TKR using the same implant and software (group II). The indication for TKR in all group II patients was atraumatic arthritis and surgery was performed in the same period as the study group. Patients were matched for age, gender, pre-operative range of motion, severity of arthritis pre-operatively, type and grade of deformity and implant features. ResultsThere were no statistically significant differences in surgical time, hospital staying or intra-operative and post-operative complications between the two study groups. At the latest follow-up no statistically significant difference was seen for the Knee Society Score and WOMAC indices. Implant alignment and radiological parameters were similar in both groups. ConclusionsThis study demonstrated that post-traumatic knee arthritis following prior distal femoral fracture can be safely managed using a computer navigated TKR without hardware removal. Comparison between this patient group and a matched group with atraumatic arthritis showed similar post-operative results and complication rates.Level of evidence: III.

Computer-assisted total knee replacement in patients with arthritis and a recurvatum deformity

We retrospectively reviewed the records of 1150 computer-assisted total knee replacements and analysed the clinical and radiological outcomes of 45 knees that had arthritis with a pre-operative recurvatum deformity. The mean pre-operative hyperextension deformity of 11° (6° to 15°), as measured by navigation at the start of the operation, improved to a mean flexion deformity of 3.1° (0° to 7°) post-operatively. A total of 41 knees (91%) were managed using inserts ≤ 12.5 mm thick, and none had mediolateral laxity > 2 mm from a mechanical axis of 0° at the end of the surgery. At a mean follow-up of 26.4 months (13 to 48) there was significant improvement in the mean Knee Society, Oxford knee and Western Ontario and McMaster Universities Osteoarthritis Index scores compared with the pre-operative values. The mean knee flexion improved from 105° (80° to 125°) pre-operatively to 131° (120° to 145°), and none of the limbs had recurrent recurvatum. These early results show that total knee replacement using computer navigation and an algorithmic approach for arthritic knees with a recurvatum deformity can give excellent radiological and functional outcomes without recurrent deformity.

A prospective study comparing the functional outcome of computer-assisted and conventional total knee replacement

A prospective study comparing the functional outcome of computer-assisted and conventional total knee replacement

Adjustable cutting blocks improve alignment and surgical time in computer-assisted total knee replacement

Computer navigation increases accuracy and precision of component alignment in total knee arthroplasty (TKA) compared to the manual technique, but is often associated with increases in surgical time. In a previous cadaver study, we demonstrated a significant improvement in guide positioning precision, final bone cut precision, and procedure length when using adjustable cutting blocks (ACB) compared to conventional cutting blocks (CCB) in computer-navigated TKA. The aim of this study was to evaluate the use of ACB in vivo. We radiographically compared component alignment and mechanical leg alignment, as well as tourniquet time, in 94 patients who underwent TKA using either ACB (N = 30) or CCB (N = 64). Postoperative mechanical alignment variability was significantly less in the ACB group (SD = 1.7°) than in the CCB group (SD = 2.7°). Tourniquet time was significantly reduced by 14.8 min in the ACB group compared to the CCB. Differences in component alignment were not significant. ACB for TKA significantly reduced postoperative mechanical alignment variability and tourniquet time compared to conventional navigated instrumentation, while providing equal or better component alignment. III.

A five to seven year follow-up comparing computer-assisted vs freehand TKR with regard to clinical parameters

Computer-assisted knee surgery has become established in routine clinical practice. Still, there is no study investigating midterm clinical outcome after five to seven years postoperatively. We aimed to test the hypothesis that there is no difference either for subjective [Western Ontario and McMaster Universities (WOMAC) scores] or for objective (Knee Society Score, degree of flexion) criteria between computer-assisted total knee replacement (TKR) and freehand TKR after 5.6-7.3 years. We performed a matched-pair analysis; 100 patients who received a primary TKR were investigated after a median follow-up of 6.25 years. Group A was operated on with the support of a computer system, while surgery on patients in group B was performed with the freehand technique. We determined WOMAC Score, Knee Society Score and degree of flexion. Overall we found similar results for WOMAC Score [group A: 42.98 (SD 13.80); group B: 41.54 (SD 15.01; p = 0.62)], Knee Society Score [group A: 168.20 (SD 21.94); group B: 166.60 (SD 21.44; p = 0.71)] and range of motion [group A: 106° (SD 9.19); group B 107° (SD 7.44; p = 0.62)]. No significant differences in midterm clinical outcome were found after TKR performed in the freehand vs computer-assisted technique.

Total knee replacement in patients with significant femoral bowing in the coronal plane

We conducted a retrospective study to investigate the effect of femoral bowing on the placement of components in total knee replacement (TKR), with regard to its effect on reestablishing the correct mechanical axis, as we hypothesised that computer-assisted total knee replacement (CAS-TKR) would produce more accurate alignment than conventional TKR. Between January 2006 and December 2009, 212 patients (306 knees) underwent TKR. The conventional TKR was compared with CAS-TKR for accuracy of placement of the components and post-operative alignment, as determined by five radiological measurements. There were significant differences in the reconstructed mechanical axes between the bowed and the non-bowed group after conventional TKR (176.2° (SD 3.4) vs 179.3° (SD 2.1), p < 0.001). For patients with significant femoral bowing, the reconstructed mechanical axes were significantly closer to normal in the CAS group than in the conventional group (179.2° (SD 1.9) vs 176.2° (SD 3.4), p < 0.001). Femoral bowing resulted in inaccuracy when a conventional technique was used. CAS-TKR provides an effective method of restoring the mechanical axis in the presence of significant femoral bowing.

The prevalence of cognitive dysfunction after conventional and computer-assisted total knee replacement

Post operative cognitive dysfunction (POCD) is common following lower limb arthroplasty. The prevalence varies from 41–75% at 7 days to 18–45% at 3 months post operatively. The wide range of prevalence is due to inconsistencies in defining and quantifying POCD. The aim of this study is to ascertain an accurate prevalence of POCD in patients who had either conventional TKR ( n = 31) or computer-assisted TKR ( n = 30). Cognition was assessed pre-operatively, 6 days and at 6 months post-operatively by a battery of 11 validated neuropsychological tests. We found the mean prevalence of POCD to be 72% at 6 days and 30% at 6 months post-operatively. When comparing the prevalence of POCD between the two groups, we found no statistically significant difference at 6 days or at 6 months post-operatively. The only statistically significant factor between the two groups was the mean procedure time which was longer in the computer-assisted TKR group ( p = < 0.001). We found a correlation between procedure time and the prevalence of POCD at 6 days ( p = 0.02) but not 6 months ( p = 0.26). POCD occurs in approximately one-third of TKR patients at 6 months post-operatively. The cause is undoubtedly multi-factorial; however we have demonstrated that procedure time may be a contributing factor. Our results suggest that using an intra-medullary femoral jig has no effect on POCD. Further research into the cognitive effects following TKR with and without a tourniquet would be of benefit.

Relationship between cutting errors and learning curve in computer-assisted total knee replacement

Computer-assisted total knee replacement (TKR) has been shown to improve radiographic alignment. Continuous feedback from the navigation system allows accurate adjustment of the bone cuts, thus reducing errors. The aim of this study was to determine the impact of experience both with computer navigation and knee replacement surgery on the frequency of errors in intraoperative bone cuts and implant alignment. Three homogeneous patient groups undergoing computer assisted TKR were included in the study. Each group was treated by one of three surgeons with varying experience in computer-aided and knee replacement surgery. Surgeon A had extensive experience in knee replacement and computer-assisted surgery. Surgeon B was an experienced knee replacement surgeon. A general orthopaedic surgeon with limited knee replacement surgery experience performed all surgeries in group C. The cutting errors and the number of re-cuts were determined intraoperatively. The complications and mean surgical time were collected for each group. The postoperative frontal femoral component angle, frontal tibial component angle, hip-knee-ankle angle and component slopes were evaluated. The results showed that the number of cutting errors were lowest for TKR performed by the surgeon with experience in navigation. This difference was statistically significant when compared to the general orthopaedic surgeon. A statistically significant superior result was achieved in final mechanical axis alignment for the surgeon experienced in computer-guided surgery compared to the other two groups (179.3 degrees compared to 178.9 degrees and 178.1 degrees ). However, the total number of outliers was similar, with no statistically significant differences among the three surgeons. Experience with navigation significantly reduced the surgical time.

Prothèse totale du genou assistée par ordinateur : douze ans d’expérience grenobloise

Computer-assisted total knee arthroplasty was developed in Grenoble in the mid-1990s. The first human implantation was performed on 21 January 1997, with no particular problems. Since this date more than 200,000 patients have been implanted with our device all over the world. The device is passive (not active like a robot), and requires no pre- or perioperative imaging. It is based on kinematics and palpation, the surgeon remaining in charge at all times. The computer helps to identify the lower leg axis, to accurately fix the bone cutting guides, and to check the ligament balance. These steps are not easy to perform with conventional ancillaries. The effectiveness of computer-assisted total knee replacement is well documented, although it is too early to claim that a "well-aligned" prothesis will have a better survival rate. Long-term follow-up studies are needed, with modern prostheses, to confirm the results of historical studies.

Navigation knee replacement

Total knee replacement (TKR) achieves an immediate and exceptional restoration in the quality of life that is comparable only to a few other procedures. It has been suggested that the most common cause of revision TKR is error in surgical technique, from malpositioning of the components which results in a poorer post-operative outcome. Based on the theoretical assumption that the use of computer-assisted systems (CAS) in TKRs may improve implant alignment and thus implant longevity, the use of this technology is becoming increasingly popular. This article (a) reviews whether computer-assisted TKR (CASTKR) results in improved prosthesis alignment compared with the conventional technique, (b) assesses the functional and clinical outcomes of CASTKR and (c) evaluates the cost-effectiveness of using this technology.

Post-traumatic osteoarthritis of the knee

Different studies confirmed the increased radiological implantation accuracy for computer-assisted total knee replacements. There was no study stating a significant influence of the navigation technique for total knee arthroplasties on the early clinical outcomes. In these two case reports we try to show special indications for a navigated total knee replacement to utilize the benefits of a navigation system as efficiently as possible.Case 1 had a femoral neck fracture 3 years ago and was treated with a long femoral gamma nail. The hardware was still retained. Case 2 had a fracture of the femoral diaphysis 31 years ago and showed an extra-articular deformity in the frontal and sagittal planes. Both patients developed osteoarthritis of the ipsilateral knee and were implanted with a total knee prosthesis using a navigation system.In both cases the prosthesis components showed perfect radiological alignment. The clinical outcomes at the 3-month follow-up were very satisfying. In case 1 the femoral nail did not have to be removed, thus decreasing surgery duration by 40-60 min.In both cases, the impossibility of using a femoral intramedullary alignment rod could be compensated for by the navigation system.

Embolic phenomena during computer-assisted and conventional total knee replacement

Embolic phenomena during computer-assisted and conventional total knee replacement

Computer-assisted alignment system for tibial component placement in total knee replacement: a radiological study

In total knee replacement (TKR), regarding tibial component positioning, almost all implants offer both an intramedullary and an extramedullary alignment guide, leaving it up to the surgeon which guide to use. However, early failure in TKR can be caused by incorrect positioning or orientation with poor limb alignment. Recently computer-based alignment systems have been developed to help the surgeon to overcome these complications. The Authors retrospectively analysed their experience using a computer-based CT-free alignment system. They assessed the radiological alignment of the tibial components in 38 computer-assisted TKR 6 months after surgery. The frontal tibial component angle (FTC) and the sagittal orientation of the tibial component (slope) were evaluated 6 months after the operation. The results were compared to those achieved with traditional alignment systems. The surgical time was statistically longer in the computer-assisted group but in this group all the tibial components were aligned within 4 degrees of all the ideal measurements in both frontal and sagittal planes.

Complications of fixed infrared emitters in computer-assisted total knee arthroplasties

BackgroundThe first stage in the implant of a total knee arthroplasty with computer-assisted surgery is to fasten the emitters to the femur and the tibia. These trackers must be hard-fixed to the bone. The objectives of our study are to evaluate the technical problems and complications of these tracker-pins, the necessary time to fix them to the bone and the possible advantages of a new femoral-fixed tracker-pin.MethodsThree hundred and sixty seven tracker-pins were used in one hundred and fifty one computer-assisted total knee replacements. A bicortical screw was used to fix the tracker to the tibia in all cases; in the femur, however, a bicortical tracker was used in 112 cases, while a new device (OrthoLock) with percutaneous fixation pins was employed in the remaining 39.ResultsTechnical problems related to the fixing of the trackers appeared in nine cases (2.5%). The mean surgery time to fix the tracker pin to the tibia was 3 minutes (range 2–7), and 5 minutes in the case of the femoral pin (range: 4–11), although with the new tool it was only three minutes (range 2–4) (p < 0.001). No complications were observed with this new device.ConclusionThe incidence of problems and complications with the fixing systems used in knee navigation is very small. The use of a new device with percutaneous pins facilitates the fixing of femoral trackers and decreases the time needed to place them.