Incidence, indications, outcomes, and survivorship of stems in primary total knee arthroplasty

Are Femoral Stems in Primary Total Knee Arthroplasty Cost Effective in High Fracture Risk Patients? A Risk Model and Cost Analysis

Femoral stemmed total knee arthroplasty (FS TKA) may be used in patients deemed higher risk for periprosthetic fracture (PPF) to reduce PPF risk. However, the cost effectiveness of FS TKA has not been defined. Using a risk modeling analysis, we investigate the cost effectiveness of FS in primary TKA compared with the implant cost of revision to distal femoral replacement (DFR) following PPF. A model of risk categories was created representing patients at increasing fracture risk, ranging from 2.5 to 30%. The number needed to treat (NNT) was calculated for each risk category, which was multiplied by the increased cost of FS TKA and compared with the cost of DFR. The 50th percentile implant pricing data for primary TKA, FS TKA, and DFR were identified and used for the analysis. FS TKA resulted in an increased cost of $2,717.83, compared with the increased implant cost of DFR of $27,222.29. At 50% relative risk reduction with FS TKA, the NNT for risk categories of 2.5, 10, 20, and 30% were 80, 20, 10, and 6.67, respectively. At 20% risk, FS TKA times NNT equaled $27,178.30. A 10% absolute risk reduction in fracture risk obtained with FS TKA is needed to achieve cost neutrality with DFR. FS TKA is not cost effective for low fracture risk patients but may be cost effective for patients with fracture risk more than 20%. Further study is needed to better define the quantifiable risk reduction achieved in using FS TKA and identify high-risk PPF patients.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Single-stage long-stem total knee arthroplasty in severe arthritis with stress fracture: a systematic review

PURPOSE

Proximal tibia stress fractures present a challenge when performing total knee arthroplasty (TKA) in knee arthritis (KA). The literature on treatment modalities for stress fractures with arthritis is varied and not systematically reviewed. We aimed to answer the questions: (1) Is long-stem TKA sufficient for stress fractures in arthritic knees? (2) Should stress fracture and KA be addressed simultaneously? (3) What is the role of augmentative procedures in stress fractures with knee arthritis? (4) Can a unified algorithm be established?

METHODS

The PubMed and Cochrane databases were searched for keywords such as stress fracture, knee arthritis and total knee arthroplasty, published from January 1995 to 29 May 2022. A total of 472 records were screened down to 13 articles on the basis of our selection criteria. Ten data items were recorded from the included studies. The methodological index for non-randomised studies (MINORS) score for the included studies was 17 ± 3.

RESULTS

We found long-stem TKA to be sufficient for most cases and advocated for single-stage treatment of stress fractures and arthritis. Augmentative procedures play a role in the treatment, and a unified algorithm was drafted to guide treatment.

CONCLUSION

Single-stage management of advanced KA with a stress fracture causes less morbidity than a staged procedure. Long-stem TKA, with or without an augmentative procedure, is an excellent option.

Similar outcomes to primary total knee arthroplasty achievable for aseptic revision using the same primary posterior-stabilised prosthesis at a mean follow-up of 49 months

PURPOSE

The aim of the study was to compare clinical and radiological outcomes between primary and aseptic revision TKAs using the same posterior-stabilised (PS) prosthesis. The authors hypothesised similar outcomes between both groups for selected patients.

METHODS

This retrospective, case-control study assessed 36 patients who underwent aseptic revision TKA compared to a match group of 72 primary TKA. Both groups had the same PS design implant (ANATOMIC®, Amplitude, Valence, France). The International Knee Society (IKS) score, radiological outcomes (postoperative alignment, patellar tilt and radiolucent lines), re-intervention and revision rate were compared between the two groups with a minimum follow-up of 3 years.

RESULTS

The final study cohort included 29 patients and 63 patients respectively in the revision and primary group, with a mean follow-up of 49.1 months (range 36.1-69). Postoperatively, there was no significant difference in IKS scores between the two groups [169.8 for the revision group and 179.6 for the primary group (p = 0.09)]. No statistical difference was observed for post-operative satisfaction 86.2% versus 92.1% (p = 0.46). Between the two groups, there was no difference in mean radiological assessment, including radiolucent lines (p = 0.7). There was no significant difference for overall implant survivorship 96.5% versus 100% (p = 0.13) at 36 months.

CONCLUSION

Similar clinical, radiological and survivorship outcomes were found between rTKA and primary TKA groups using the same PS level of constraint in patients undergoing revision surgery for aseptic indications at 3-year follow-up. Use of PS implants in rTKA for the correct indication suggests this to be a safe approach at least in the medium term.

LEVEL OF EVIDENCE

IV, retrospective case-control study.

Tibial Tray with a Stem: Does It Have Any Role in Primary Cemented Total Knee Replacement?

Over many decades, total knee replacement (TKR) has become the ideal treatment option for advanced arthritis. Many designs were introduced to increase the stability of the tibial tray, hence the longevity of the prosthesis. This retrospective study was performed on 168 patients who received NexGen cemented primary total knee either with standard tibial tray (group A) or tibial tray with an intramedullary stem (group B) between May 2008 and May 2017. We reviewed all preoperative and postoperative clinical and radiological data retrospectively. In addition, a prospective clinical and radiological reassessment was done. Our aim was to answer the following questions: (1) Is there any difference between both groups in regard to clinical and radiological results? (2) Is there any difference in the revision rate? (3) Is there a role of using stemmed tibial tray in primary TKR? Better results were recorded in obese and severely obese patients having stemmed cemented tibial tray and so for patients with marked and severe preoperative varus angle. Our recommendations are to use cemented tibial tray with a stem in complicated primary surgery without fear of adverse effects on short and intermediate terms of follow-up.

Primary total knee arthroplasty in tibial plateau fractures: Literature review and our institutional experience

BACKGROUND

Displaced proximal tibia fractures in the elderly may be very difficult to manage. If osteosynthesis represents the standard of care in the younger patients, in the aged population this solution is controversial because a significant failure rate has been reported after internal fixation. Moreover, osteoarthritis progression following tibial plateau fractures is common, often requiring a subsequent total knee arthroplasty (TKA). In recent years, in order to overcome the fracture healing problems and to allow immediate full weight bearing, primary TKA after tibial plateau fractures in elderly patients has gained popularity.

MATERIAL AND METHODS

from 2015 to 2019, 11 tibial plateau fractures in elderly patients with pre-existing osteoarthritis were treated with a primary TKA. Age, gender, mechanism of trauma, pre-operative autonomy level, fractures classification, degree of osteoarthritis and intraoperative data (ligamentous stability and type of implant) were collected. After a mean follow-up of 28 months, Knee Society Score (KSS), post-operative autonomy level and Forgotten Joint Score (FJS) were evaluated. The radiological assessment (signs of loosening, limb axis and patellar height indices) and complications were also recorded.

RESULTS

according to fracture type and ligamentous competence, 6 cases of posterior-stabilized (PS) design and 5 cases of semi-constrained TKA were implanted. At the final follow up, mean KSS knee score was 83±16 and mean KSS functional score was 74±15. Mean pre-operative autonomy level assessed with the Parker scale, was significantly higher than the post-operative one (7.5±1.4 vs 5.6 ± 1.3). Mean FJS was 66 ± 14. No lines of radiolucency or limb malalignment were found at the final radiological follow-up. One major complication was recorded: one acute periprosthetic infection. One patient reported a periprosthetic femoral fracture after 26 months.

CONCLUSION

Based on our and results and those reported on literature, primary TKA is a suitable option in case of tibial plateau fractures in elderly patients with pre-existing osteoarthritis and poor bone quality, in which osteosynthesis outcome may be poor. Unlike ORIF, primary TKA may allow immediate weightbearing and a faster recovery. Nevertheless, it is a demanding surgery with a significant complications rate and should be reserved for selected patients and experienced surgeons.

Total Knee Arthroplasty Is Superior to Open Wedge High Tibial Osteotomy in Terms of Pain Relief for Patients With Osteoarthritis

Background

Globally, total knee arthroplasty (TKA) is widely performed on patients with osteoarthritis. Meanwhile, open wedge high tibial osteotomy (OWHTO) has garnered attention in our country as a joint-preserving procedure. This study aimed to retrospectively compare the postoperative clinical outcomes of TKA and OWHTO for patients with osteoarthritis.

Methods

We selected 94 patients (106 knees) who underwent OWHTO or TKA between 2013 and 2018, had complete clinical data, and were followed up for >2 years. Patients were classified into 2 groups depending on the procedure (TKA: n = 49; OWHTO: n = 45). Patients in the A (= arthroplasty) group were significantly older, with a worse range of motion (ROM) than those in the O (osteotomy) group. There were no significant differences regarding sex and body mass index between groups. Operative time, perioperative blood loss, knee ROM, and Japanese Knee Injury and Osteoarthritis Outcome Score (J-KOOS) were compared between the groups.

Results

Significant differences were found between the A and O groups regarding operative time (120 ± 27.2 vs 80.3 ± 23.3 minutes), perioperative blood loss (505.4 ± 271.8 vs 322.6 ± 196.1 mL), knee ROM (flexion; 123.4 ± 16.3° vs 133.7 ± 12.8°), and J-KOOS for pain (87.4 ± 12.5 vs 78.1 ± 15.2 points) and symptoms (86.6 ± 12.3 vs 79.1 ± 13.3 points). There were no significant differences regarding other J-KOOS subscales.

Conclusions

OWHTO involved shorter operative times and less blood loss. However, the O group reported less pain relief. The A group represents an older, likely less active patient population. Therefore, OWHTO is a possible joint-preserving treatment options in younger active patients who may not be interested in arthroplasty.

Increased survival rate in extension stemmed TKA in obese patients at minimum 2 years follow-up

PURPOSE

Total knee arthroplasty (TKA) is frequently performed for obese patients. TKA in this population shows a high rate of complication, particularly tibial component loosening. The aim of this study is to compare the survival rate of tibial components in obese population using TKA with stem versus without stem.

METHODS

From a prospective database of 4216 TKA, obese patients [body mass index (BMI) > 30 kg m²] with primary TKA using a tibial short stem extension (30 mm) at a minimum follow-up of 2 years were retrospectively reviewed and compared to a matched control group (1:3 ratio) with a standard tibial stem. Inclusion criteria were BMI > 30 kg m², first knee surgery and 24 months minimum of follow-up. The primary outcome was revision for tibial aseptic loosening. Secondary outcomes were all-cause revisions and Knee Society Scores (KSS).

RESULTS

The final study population consisted of 35 TKA with tibial extension stem versus 105 TKA with standard stem. The mean age was 69.2 and 69.5 years, respectively, with a mean follow-up of 52 months. Both groups were comparable before surgery. After 2 years of follow-up, we observed seven tibial loosening in the group without stem (6.6%) versus no tibial loosening in the stemmed group (p < 0.001). The difference in KSS knee score (83 versus 86; p = 0.06) and the KSS function score (73 versus 77; p = 0.84) were not statistically significant at the final follow-up.

CONCLUSION

Using stemmed TKA for obese patients significantly decreased tibial loosening rate at minimum 2 years of follow-up.

LEVEL OF EVIDENCE

Case-control study, Level III.

Increased survival rate for primary TKA with tibial short extension stems for severe varus deformities at a minimum of 2 years follow-up

PURPOSE

The purpose of this study was to compare the clinical results, radiographic loosening and early complications between patients undergoing primary knee arthroplasty (TKA) with tibial short stem extension and those with standard stem for gross varus deformities at minimum two years after surgery.

METHODS

From a prospective TKA database of 4216 patients, patients with a primary TKA with a tibial short stem extension (30 mm) for severe varus deformity (hip-kneeankle angle, HKA < 170°) and a minimum follow-up of 2 years, were reviewed and compared to a matched control group with tibial components with a standard stem, in a 1:3 ratio. Demographics, surgical parameters, pre- and postoperative alignment and outcome parameters were collected for all patients. The primary outcome was aseptic loosening of the tibial component. Secondary outcomes were knee society scores (KSS), postoperative HKA, general postoperative complications and implant survival rates.

RESULTS

Forty-five patients with tibial short stem extensions (mean HKA 166.2°) were compared in a 1:3 ratio to a matched case-control group of 135 patients with standard stems (mean HKA 167.1°) at a mean follow-up of 57 and 64 months respectively after primary TKA. In the extension stem group, 4 patients encountered complications (8.9%) versus 12 patients in the standard stem group (8.9%). There were no cases of tibial component loosening in the short extension stem versus four cases in the standard stem group (3%). This difference was significant between groups, p = 0.04.

CONCLUSION

In patients with varus deformities > 10°, undergoing primary total knee arthroplasty, prophylactic use of a tibial short extension stem may lead to less loosening of the tibial component. In this study, 3% of patient with big varus deformity without stemmed TKA had a tibial implant loosening versus 0% in the stemmed TKA group.

LEVEL OF EVIDENCE

Level III, case-control study.

Primary cementless total knee arthroplasty with or without stem extension: a matched comparative study of ninety eight standard stems versus ninety eight long stems after more than ten years of follow-up

INTRODUCTION

Using a cementless fixation for total knee arthroplasty (TKA) is controversial. We hypothesized that cementless tibial base plate with a monoblock long stem (MLS) would provide secure tibial alignment and stable fixation when bone conditions were considered as poor for a cementless fixation. The purpose of this study was to compare the mean eight year survivorship of cementless standard keels (SK) vs cementless MLS.

MATERIAL METHODS

We report a matched series of 98 cases of SK and 98 cases of MLS in patients with poor bone conditions. The two cohorts were statistically compared. Revision for tibial loosening was used as the endpoint in the survivorship analysis.

RESULTS

We recorded two cases of tibial loosening and three cases of bipolar loosening in the SK group (0% MLS vs 5% SK). No tibial loosening occurred in the MLS group (statistically significant). No tibial periprosthetic or intra-operative fractures occurred in either group. The survivorship at eight years of follow-up was 95.6% in the SS cohort vs 100% in the MLS cohort using revision for tibial loosening as the endpoint.

DISCUSSION

This study was not randomized. Its strength was that it took into account the comparative midterm outcomes of a matched cohort of patients implanted with two types of cementless components in the same bone conditions. We did not record any tibial loosening in the MLS group. Using long stems has been criticized but we did not observe any adverse reactions and no intra-operative tibial fracture occurred.

CONCLUSION

MLS improves the alignment and fixation of cementless TKA. This is a safe solution when bone conditions are poor or modified by previous surgery.

Optimum stem length for mitigation of periprosthetic fracture risk following primary total knee arthroplasty: a finite element study

PURPOSE

Due to age-related changes to the material properties and thinning of the cortical bone structure, older patients with osteoporosis may be at greater risk of femoral fracture following total knee arthroplasty. This study investigates whether there is a potential role for stemmed prostheses in such scenarios to help mitigate peri-implant fracture risk, and if so what should the optimum stem length be to balance surgical bone loss with reduced fracture risk.

METHODS

Finite element models of the distal femur implanted with four different implant types: a posterior stabilising implant, a total stabilising implant with short stem (12 mm × 50 mm), a TS implant with medium stem (12 mm × 75 mm), and a TS implant with long stem (12 mm × 100 mm), were developed and analysed in this study. Osteoporotic properties were applied to the implanted femurs and the periprosthetic stresses and strains of each were recorded.

RESULTS

All stem lengths examined were found to lead to a reduction in periprosthetic stress in comparison with a primary stemless implant, with short-, medium-, and long-stemmed implants leading to an 11, 26, and 29% reduction in stress, respectively.

CONCLUSION

The results of this study show that periprosthetic stress and therefore fracture risk in old osteoporotic patients may be reduced through the use of stemmed femoral components. Of the three stems investigated, a medium-length stem is found to represent the best balance between bone preservation at the time of surgery and reduction in periprosthetic stress following implantation.