Total knee replacement in the obese patient: comparing computer assisted and conventional technique

Challenges and Solutions: Total Knee Replacement in Patients with Chronic Lymphatic Filariasis: A Case Report

CASE

A 59-year-old woman with a history of left knee pain exacerbated by lymphatic filariasis underwent successful total knee replacement (TKR) for advanced osteoarthritis. Postoperatively, diligent adherence to compression bandaging, physiotherapy, and lymphatic flow promotion resulted in no lymphedema progression. During the 5-year follow-up, the patient showed improved Knee injury and Osteoarthritis Outcome Score and stable implant.

CONCLUSIONS

Currently, there are no established protocols or formulated guidelines for TKR in patients with chronic filariasis. The preoperative lymphedema prevention must be tailor-made for each patient in the context of advanced osteoarthritis based on the functional lymphatic vessel status.

Robotic-Assisted Total Knee Arthroplasty in Obese Patients

Background

Robotic-assisted systems have gained popularity in total knee arthroplasty (TKA). The purpose of this study was to evaluate operative characteristics and radiographic outcomes of obese patients undergoing robotic-assisted TKA.

Methods

A retrospective review of consecutive cases performed by a single surgeon was performed from January 1, 2016, to January 31, 2022. Adult patients with body mass index ≥35 kg/m2 who underwent primary TKA using a computed tomography-assisted robotic system were compared to patients who underwent primary TKA using conventional instrumentation. Demographics, preoperative and postoperative radiographic measurements, and intraoperative outcomes were compared between cohorts. In total, 119 patients were identified, 60 in the robotic-assisted cohort and 59 in the conventional instrumentation cohort.

Results

Age, body mass index, and estimated blood loss were not significantly different between the cohorts. The robotic-assisted cohort experienced longer tourniquet times (93.3 vs 75.5 minutes, P < .001). Preoperative hip-knee-ankle angle (HKA) was similar between the robotic-assisted and conventional cohorts (8.4° ± 4.9° vs 9.3° ± 5.3°, P = .335). Postoperative HKA was 2.0° ± 1.4° in the robotic-assisted group and 3.1° ± 3.23° in the conventional group (P = .040). The proportion of patients with postoperative HKA > 3° of varus or valgus was 9 of 60 (15.0%) in the robotic-assisted cohort compared to 18 of 59 (30.5%) using conventional instrumentation (P = .043).

Conclusions

Obese patients treated with robotic-assisted TKA had postoperative alignment closer to neutral and fewer postoperative radiographic outliers than patients treated with conventional instrumentation. The results of this study support use of robotic-assisted technologies in TKA, particularly in obese patients.

Total Hip and Knee Arthroplasty Surgery in the Morbidly Obese Patient: A Critical Analysis Review

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Obesity, defined as body mass index (BMI) ≥30, is a serious public health concern associated with an increased incidence of stroke, diabetes, mental illness, and cardiovascular disease resulting in numerous preventable deaths yearly.

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From 1999 through 2018, the age-adjusted prevalence of morbid obesity (BMI ≥40) in US adults aged 20 years and older has risen steadily from 4.7% to 9.2%, with other estimates showing that most of the patients undergoing hip and knee replacement by 2029 will be obese (BMI ≥30) or morbidly obese (BMI ≥40).

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In patients undergoing total joint arthroplasty (TJA), morbid obesity (BMI ≥40) is associated with an increased risk of perioperative complications, including prosthetic joint infection and mechanical failure necessitating aseptic revision.

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The current literature on the role that bariatric weight loss surgery before TJA has on improving surgical outcomes is split and referral to a bariatric surgeon should be a shared-decision between patient and surgeon on a case-by-case basis.

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Despite the increased risk profile of TJA in the morbidly obese cohort, these patients consistently show improvement in pain and physical function postoperatively that should be considered when deciding for or against surgery.

Novel clinical and radiological measures of lower limb obesity

Osteoarthritis of the knee is strongly associated with central obesity, and the prevalence of obesity in patients undergoing knee arthroplasty procedures is expected to increase. Central obesity is associated with multiple adverse outcomes after knee arthroplasty, but the impact of obesity specifically around the operated knee is poorly understood. One reason for this is the absence of a standardized measure, analogous to BMI for central obesity, to facilitate research. The aim of this study was to develop a radiological limb obesity scoring system which reliably corresponds with anthropometric measurements. Detailed anthropometric and radiological measurements were taken from patients undergoing total and unicompartmental knee replacement. Anthropometric measurements were combined into a composite score using principal components analysis. Different radiological scoring methods were evaluated against the anthropometric measure using correlation and regression analyses. Intraclass correlation coefficients were used to evaluate intra- and inter-observer reliability of the radiographic measurements. Measurements were obtained from fifty patients. There was a significant correlation between the composite anthropometric score and unadjusted radiological soft tissue width at the level of the femoral condyles (p < 0.001). There was also a significant correlation with the ratio of tissue to bone widths at the same level (p < 0.001), and fit was improved by including variables coding for soft tissues overlapping the medial or lateral boundaries of the radiograph. We have demonstrated a methodology for producing standardized radiological limb obesity scores which are strongly correlated with anthropometric measurements, and which can be easily applied in diverse clinical and research settings.

No influence of obesity on mid-term clinical, functional, and radiological results after computer-navigated total knee arthroplasty using a gap balancing technique

OBJECTIVE

In obese patients, thick subcutaneous tissue can introduce errors during registration and leg weight can influence gap balancing in navigated TKA. Present study is done to determine if computer navigated TKA using a gap balancing technique can achieve consistent accuracy for limb and component alignment, and similar clinical and functional results in obese patients like in non-obese patients.

METHODS

We prospectively compared the radiological, clinical, and functional results of 78 knees in 57 non-obese patients and 79 knees in 58 obese patients who underwent computer-assisted TKA. Non-obese individuals were defined as those having BMI of <30 kg/m² and obese individuals as BMI ≥30 kg/m². The degree of knee deformity was calculated by Hip - Knee - Ankle (HKA) angle and clinical and functional assessment was done using the Knee Society Score - clinical knee score and Knee Society Score - function score, respectively. All these were documented before and at 6 months, 2 year, and 5 years after TKA.

RESULTS

The outlier rate of postoperative limb alignment (HKA angle) was 8.9% in the obese group which was not significantly different (p =1.00) from that of the non-obese group (7.7%). Mean clinical knee scores were not significantly different between the non-obese and obese groups preoperatively (58.8 vs 57.4, p = 0.14) and at 6 months (92.7 vs 91, p = 0.06), 2 years (91.4 vs 90, p = 0.07), and 5 years (92.4 vs 91.3, p = 0.1) post-surgery. Similarly, mean functional scores were not significantly different between the non-obese and obese groups preoperatively (50.9 vs 49.9, p = 0.31) and at 6 months (92.7 vs 90.9, p = 0.06), 2 years (91.3 vs 92, p = 0.44), and 5 years (90.6 vs 91.1, p = 0.51) post-surgery.

CONCLUSION

Obesity has no influence on mid-term clinical, functional, and radiological results after computer navigated TKA, done by gap balancing technique.

LEVEL OF EVIDENCE

Therapeutic level II.

Clinico-Radiological and Functional Results of the Navigated Gradius (Gradually Reducing Radius) Knee Prosthesis at Short to Mid-Term Follow-Up

BACKGROUND

Navigated total knee replacements (TKR) have shown better knee function and quality of life. It also reduces revision rates. The aim of our study is to evaluate short to mid-term clinico-radiological and functional results, survival rate and complications of Gradius knee prosthesis implanted using computer navigation.

METHODS

We retrospectively reviewed 120 Gradius knee prosthesis, implanted in 68 patients (52 bilateral TKR and 16 unilateral TKR) and followed from Jan 2015 till Jan 2020. Pre-operative & post-operative radiographs, knee society scores (KSS), range of motion (ROM), deformity assessment and gait video recordings were done for all patients.

RESULTS

The mean follow-up was 3.8 years (minimum 2-5 years).The mean ROM was 2° (0-10) extension to 135° (128°-138°) flexion. The KSS pain score improved from mean of 38.3 (range 26-44) to 90.4 (mean 88-92). The KSS functional score improved from 36.2 (range 28-39) to 92.6 (range 86-94). All patients had excellent to good function during successive follow-ups. The coronal alignment improved from 8° varus to 0.3° varus. Sagittal alignment was corrected from 8° (4°-18°) preoperatively to 2° (0°-8°) postoperatively.

CONCLUSION

At mid-term our series outlines the better functional and radiological results of Gradius knee prosthesis using navigation as a tool. We recommend a prospective randomized controlled trials comparing navigated versus non-navigated for Gradius knee prosthesis with long-term follow-up.

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.

Morbid Obesity and Total Knee Arthroplasty: A Growing Problem

Obesity is an epidemic, with approximately 35% of the US population affected. This rate is unlikely to decline and may increase the demand for total knee arthroplasty (TKA). Data regarding the risks, benefits, and potential complications of TKA in this patient population are conflicting. Preoperative considerations are optimization of nutritional status, safe weight loss strategies, and bariatric surgery. Intraoperative concerns unique to this population include inadequate exposure, implant alignment, and durable implant fixation; postoperative issues include tibial loosening, wound complications, cardiovascular events, and respiratory complications. A thorough understanding of the medical and surgical complications associated with TKA in the obese patient will facilitate research efforts and improve outcomes.

A Systematic Literature Review of Three Modalities in Technologically Assisted TKA

In effort to reduce the revision burden of total knee arthroplasty (TKA), industry emphasis has focused on replacing manual techniques—which are subject to variability—with technological implements. Unfortunately, technological innovation often continues before adequate time for critical evaluation has passed. Therefore, the purpose of this descriptive literature review was to collect a large sample of international data and report on the clinical and economic efficacy of three major types of technologically assisted TKA: navigation, patient-specific instrumentation, and sensorized trials.

No effect of obesity on limb and component alignment after computer-assisted total knee arthroplasty

PURPOSE

This retrospective study aimed to determine if computer navigation provides consistent accuracy for limb and component alignment during TKA irrespective of body mass index (BMI) by comparing limb and component alignment and the outlier rates in obese versus non-obese individuals undergoing computer-assisted TKA.

METHODS

Six hundred and thirty-five computer assisted total knee arthroplasties (TKAs) performed in non-obese individuals (BMI<30 kg/m(2)) were compared with 520 computer-assisted TKAs in obese individuals (BMI ≥ 30 kg/m(2)) for postoperative limb and component alignment using full length standing hip-to-ankle radiographs.

RESULTS

No significant difference in postoperative limb alignment (179.7° ± 1.7° vs 179.6° ± 1.8°), coronal femoral (90.2° ± 1.6° vs 89.8° ± 1.9°) and tibial component (90.2° ± 1.6° vs 90.3° ± 1.7°) alignment and outlier rates (6.2% vs 7.5%) was found between non-obese and obese individuals. Similarly, alignment and the outlier rates were similar when non-obese individuals and a subgroup of morbidly obese individuals (BMI >40 kg/m(2)) were compared.

CONCLUSIONS

Computer navigation can achieve excellent limb and component alignment irrespective of a patient's BMI. Although obesity may not be an indication per se for using computer navigation during TKA, it will help achieve consistently accurate limb and component alignment in obese patients.

LEVEL OF EVIDENCE

Level II.