Is BMI Outdated in TKA Patient Selection? Assessment of the Impact of Pre-tubercular Subcutaneous Tissue Thickness and the Risk of Postoperative Infection Following Total Knee Arthroplasty

NCT07763535 | Not Yet Recruiting

• 2 other identifiers: DEV144372419
• Study Type: observational
• Target: 400
• Locations: 0 countries
• Sites: N/A

Brief Summary

While Body Mass Index (BMI) is currently used as a primary tool for risk stratification in patients undergoing Total Knee Athroplasty(TKA), its limitations raise concerns regarding its accuracy and fairness in guiding surgical decision-making. In particular, reliance on BMI alone may lead to the exclusion of patients who could safely benefit from surgery, while failing to identify others at increased risk due to unfavourable local anatomical factors. Pre-tubercular subcutaneous fat thickness (PTFT) offers a simple, reproducible, and anatomically relevant measurement that directly reflects the soft tissue envelope at the operative site. As such may provide a more clinically meaningful assessment of infection risk than BMI. This study aims to evaluate the association between PTFT and postoperative infection following TKA. By doing so, it seeks to determine whether PTFT could serve as an adjunct or alternative risk stratification tool in clinical practice. The findings of this study have the potential to inform a more individualized approach to patient selection and preoperative counselling, improving shared decision-making and resource utilisation.

Conditions

Knee Arthritis Osteoarthritis; Knee Replacement Arthroplasty; BMI; Regional Body Composition; Periprosthetic Infection

Keywords

Total Knee Replacement; Knee Arthritis; Regional anatomy; BMI; Periprosthetic infection

Outcome Measures

Primary Outcomes (1)

• Postoperative periprosthetic joint infection

  The primary objective is to determine whether an increase in the thickness of the soft tissue (fat) over the front of the shin bone (known as pre-tubercular subcutaneous fat thickness) as measured on a lateral pre-operative x-ray is associated with an increased risk of postoperative infection within 12 months following primary total knee arthroplasty.

  12 months from index procedure

Secondary Outcomes (3)

• BMI and risk of post-operative infection

  12 months

• BMI vs PTFT relationship

  12 months

• PTFT influence on return to theatre

  12 months

Study Arms (1)

Adults over 18 undergoing Primary Total Knee Replacement

This cohort includes adults undergoing Primary Total Knee Replacement within the defined study period meeting the exclusion and exclusion criteria. The end point is 12 months following index procedure with events of interest being periprosthetic joint infection.

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Adults aged over 18 meeting the study criteria who have undergone a primary TKR at East Lancashire Hospital NHS Trust within the defined study period will be included in the study. Patients will be identified using a combination of OPCS codes for primary TKA, theatre logs and electronic operation records. All eligible adults withint the study period will be included for analysis.

You may qualify if:

• Adults aged 18 years or older at the time of surgery
• Underwent primary total knee replacement surgery
• Procedure performed at East Lancashire Hospitals NHS Trust (Burnley General Hospital or Royal Blackburn Hospital)
• Surgery performed between 1 November 2023 and 30 November 2024
• Availability of a preoperative lateral knee X-ray to allow measurement of soft tissue thickness

You may not qualify if:

• Patients who underwent revision knee replacement surgery
• Patients who underwent partial (unicompartmental) knee replacement surgery
• Patients aged under 18 years at the time of surgery
• Primary procedure performed outside East Lancashire Hospitals NHS Trust
• Absence of a suitable preoperative lateral knee X-ray for measurement of soft tissue thickness
• Patients who have registered a National Data Opt-Out

Sponsors & Collaborators

• East Lancashire Hospitals NHS Trust: lead

Study Officials

• Lee Hoggett, MBChB, FRCS

  East Lancashire NHS Trust

  STUDY CHAIR

• Charles Hallett, MBBS, MRCS

  East Lancashire NHS Trust

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Michelle Stephens

CONTACT

+447976152397; research.sponsorship@elht.nhs.uk

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: RETROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 10, 2026
• First Posted: August 13, 2026
• Study Start: August 17, 2026
• Primary Completion (Estimated): November 1, 2026
• Study Completion (Estimated): February 1, 2027
• Last Updated: August 13, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share