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Year : 2017  |  Volume : 17  |  Issue : 3  |  Page : 135-138

Midterm functional outcomes of imageless navigation-assisted total knee arthroplasty

1 Department of Orthopedic Surgery, McGill University, Montreal, Canada
2 Department of Orthopedic Surgery, King Saud University, Riyadh, Saudi Arabia
3 Department of Rehabilitation Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia

Date of Web Publication4-Oct-2017

Correspondence Address:
Abdulrahman D Algarni
Department of Orthopedic Surgery, King Saud University, P.O. Box: 7805 (49), Riyadh 11472
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sjsm.sjsm_15_17

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Purpose: The study aims to evaluate the functional outcomes of imageless navigation-assisted total knee arthroplasty (TKA) after a minimum follow-up of 7 years.
Materials and Methods: Between December 2004 and December 2009, a total of 123 navigation-assisted TKAs in 94 patients were performed by the same surgeon at a single institution. Hospital for Special Surgery (HSS) knee score was recorded pre- and post-operatively, and radiographic assessment for osteolysis, wear, or loosening was performed in all patients.
Results: No conversion from navigation-assisted to conventional technique was required in any patient. The mean pre- and post-operative HSS score was 60.3 and 86.8, respectively. None of the patients was lost to follow-up. The survivorship of all knees at an average of 9.5 years after surgery was 99.3%. One patient required revision due to deep infection. There were no pin tracker-related complications.
Conclusions: Navigation-assisted TKA produces good clinical outcomes comparable to conventional TKA. Further studies are required to assess long-term functional outcomes.

Keywords: Computer-assisted surgery, functional outcomes, navigation, total knee arthroplasty

How to cite this article:
Reuven A, Algarni AD, Aoude A, Kachanathu SJ, Zukor DJ. Midterm functional outcomes of imageless navigation-assisted total knee arthroplasty. Saudi J Sports Med 2017;17:135-8

How to cite this URL:
Reuven A, Algarni AD, Aoude A, Kachanathu SJ, Zukor DJ. Midterm functional outcomes of imageless navigation-assisted total knee arthroplasty. Saudi J Sports Med [serial online] 2017 [cited 2023 Sep 29];17:135-8. Available from: https://www.sjosm.org/text.asp?2017/17/3/135/215915

  Introduction Top

The success of total knee arthroplasty (TKA) depends on several factors, including optimal mechanical alignment of the limb, soft-tissue balancing, and joint line restoration.[1] The optimal alignment of components following TKA is a fundamental factor for the satisfactory outcome in terms of long-term survival of the implant.[2],[3] Higher rates of revision and less satisfactory clinical results have been reported following malalignment outside a range of 3° varus or valgus.[3] Navigation-assisted TKA is expected to improve the accuracy and consistency of component alignment in TKA, which has been assessed in many comparative studies on navigation versus conventional TKA.[4],[5],[6],[7],[8] Different navigation systems exist including standard pinned image-based and imageless and, more recently, the pinless navigation systems.

Several studies have demonstrated superior alignment in the frontal plane and better restoration of the mechanical lower limb axis in navigated TKA compared with conventional TKA, with fewer outliers outside a range of 3° varus or valgus.[9],[10],[11] However, whether superior alignment or decreased proportion of outliers would result in a better clinical outcomes is unknown. In this study, therefore, we aim to evaluate the midterm functional results of our navigation-assisted TKAs.

  Materials and Methods Top

We conducted a retrospective study of all patients who received standard imageless navigated TKA (CI CT-free DePuy-Synthes/BrainLAB navigation system) from one surgeon at a single institution. All patients who received the procedure between December 2004 and December 2009 were included in the study. All patients underwent primary knee arthroplasty for severe tricompartmental disease demonstrated by clinical and radiological evaluation. Preoperative diagnoses were degenerative osteoarthritis, rheumatoid arthritis, and osteonecrosis. Our exclusion criterion was a previous TKA in the same joint. In all, 94 patients were identified accounting for 123 knees. Mean patient age was 62 years (range; 46–78) with 86% (79/94) females and 14% (15/94) males. Twenty-nine patients received bilateral procedure conducted on separate dates [Table 1].
Table 1: Patients' demographics

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All surgeries were performed by the same surgeon (the senior author) at a single institution utilizing the standard medial parapatellar quadriceps splitting approach with patella eversion under tourniquet control at 350 mmHg. All patients received a posterior-stabilized, fixed-bearing implant; Sigma-PFC (DePuy-Synthes, Warsaw, IN, USA) and closure of wounds were performed in a standard manner without a drain.

The navigation system utilized has an optical tracking unit, which detects reflecting marker spheres by an infrared camera. Two reference unicortical pins with passive marker spheres were rigidly fixed to both the femoral and the tibial bone at a sufficient distance from the wound. Anatomical landmarks and bone surface information were registered at the beginning of the procedure by sliding a pointer over the femoral condyles and the tibial plateau. Subsequently, the femoral and tibial cutting blocks were orientated to the bone in real-time visualization, and all resection planes were checked by the verification tool on the navigation system.

Patients were evaluated clinically preoperatively as well as at 6 weeks, 6 months, and 1 year postoperatively. Follow-up on every subsequent year was also scheduled for all patients. Hospital for Special Surgery knee score (HSS) was documented in the patient charts at each follow-up. Radiological evaluation was also completed at every follow-up visit to check for osteolysis, polyethylene wear, or loosening. The minimum follow-up for this study was 7 years with an average follow-up of 9.5 years (range; 7–12).

Statistical analysis was carried out using SPSS version 19.0 software (IBM, Armonk, New York, USA). Statistical significance was defined as P < 0.05. The paired t-test was used to evaluate the improvement in clinical outcomes as compared to preoperative values.

The study was approved by the Institutional Review Board, and all patients gave their informed consent before their inclusion in the study.

  Results Top

The mean time for the registration process, planning, and data transfer was 19 min (±7) and that for the whole procedure (skin to skin) was 86 min (±18). No conversion from navigation-assisted procedure to conventional technique was required in any patient.

None of the patients was lost to follow-up. The mean preoperative HSS knee score was 60.3 (standard deviation [SD]; 13.13) with 86.4% of patients had HSS score below 80. The mean postoperative HSS score was 86.8 (SD; 7.93). Of all 94 patients, 38.6% had HSS outcomes greater than 90 and 37% had HSS outcomes between 80 and 90. The HSS score tends to increase after surgery until about 1 year and then stabilize which indicates that treatment with TKA is successful in increasing patient comfort and activity over time.

There were no abnormal radiological evaluations including loosening or polyethylene wear. All implants were classified as stable, and no osteolysis was noted. With regard to complications, one patient required revision due to deep infection. Thus, the survivorship of all knees at an average of 9.5 years after surgery (range; 7–12) was 99.3%. There were no pin tracker-related complications.

  Discussion Top

In this study, we report the clinical outcomes of patients who underwent TKA using computer-assisted imageless navigation system. The use of computer assistance in arthroplasty has been the topic of much interest.[12],[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24],[25],[26],[27] It has been repeatedly stated in the literature that appropriate alignment of components, restoration of mechanical axis during the surgery, and meticulous balancing of the soft tissues contribute to the success of TKA.[12],[15],[21],[22] Upon its advent, it was believed that computer-assisted TKA may provide better execution of bony cuts and may aid in better alignment of the implanted knee. Several prospective studies and meta-analyses have failed to show a clear advantage of using computer assistance over conventional TKA and show that computer-assisted TKA results in mechanical alignment similar to that of conventional TKA.[12],[14],[24] On the other hand, several published articles report that in fact computer assistance does improve component orientation and mechanical axis restoration while significantly reducing the number of outliers compared to conventional TKA.[13],[15],[16],[20],[26],[27] Probably, these reports are true and not necessarily conflicting as the role of computer assistance might be in providing better outcomes in complex cases.[28],[29]

Our hypothesis was that TKA done using computer-assisted navigation system provides good clinical outcomes that are comparable to conventional TKA procedures. Therefore, the study reports on the success of surgery carried out with the guidance of the navigation system. We operated on 123 knees with a preoperative HSS knee score of 60.3 (SD; 13.13). The knee score improved progressively in the postoperative period, reaching a plateau of around 84.4 (SD; 9.97) one year after surgery. This improvement in knee scores was sustained with an HSS score of 87.7 (SD; 8.33) at 6 years. The narrow standard deviation of 9.97 at 1 year and 8.33 at 6 years is evident that TKAs performed using computer assistance consistently results in good outcomes with low variance. Cip et al. in a randomized comparative study found no difference between computer-assisted and conventional TKA in the clinical outcome after 5 years of follow-up.[30]

Overall, even though we did not see many complications in our study, navigation-assisted TKA does have a higher cost and requires a longer learning curve and operating times when compared to conventional TKA.[17],[18],[24] However, the additional operating time seems tolerable and may gradually decrease with improved surgeon's learning curve. Navigation-assisted TKA also has its specific complications such as pin site infection and femoral or tibial fractures through the tracker pin site.[19] Previous studies have described an incidence of 1.2% and 1.3% of pin site infection and tract-related fractures, respectively.[31],[32] The more recent pinless systems allowed navigation-assisted procedure while eliminating the pin tracker-related complications.[33]

There are certain limitations to our study. This was a retrospective cohort study, and thus carries with it, the inherent biases and flaws of any retrospective study. Furthermore, no comparative or control group exists.

  Conclusions Top

Computer-assisted TKA produces good midterm clinical outcomes that are comparable to published literature using conventional TKA; however, long-term follow-up is warranted.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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