An interventional study of Conventional Midline Incision and J-shaped Incision in Osteoarthritis, Knee, sponsored by Fatih Sultan Mehmet Training and Research Hospital. Completed at 1 site in Turkey (Türkiye). Open to participants aged 56 Years to 81 Years. Per ClinicalTrials.gov, last updated 2026-05-29.
Sponsored by Fatih Sultan Mehmet Training and Research Hospital · Not applicable, Interventional, and Treatment
This prospective randomized controlled trial evaluates whether a modified J-shaped skin incision can reduce peri-incisional numbness after primary total knee arthroplasty (TKA) compared with the conventional midline skin incision. Peri-incisional numbness is a common postoperative complaint after TKA and is thought to be mainly related to injury of the infrapatellar branch of the saphenous nerve. Although often considered a minor issue, it may adversely affect postoperative comfort, pain perception, and patient satisfaction.
A total of 62 patients undergoing primary TKA for Kellgren-Lawrence grade 4 varus knee osteoarthritis were randomized to either a conventional midline incision or a modified J-shaped incision. In the J-shaped technique, the distal part of the incision is curved laterally at the level of the tibial tuberosity in an effort to decrease injury to the infrapatellar branch of the saphenous nerve. The primary outcome is the extent of peri-incisional sensory loss, assessed using Semmes-Weinstein 10-g monofilament testing with a grid-mapping method before surgery and at 2 and 6 months after surgery. Secondary outcomes include pain scores, functional knee scores, range of motion, blood loss, tourniquet time, and wound-related complications.
Total knee arthroplasty is an effective surgical treatment for advanced knee osteoarthritis; however, peri-incisional numbness is a frequent postoperative finding. This sensory disturbance is commonly attributed to injury of the infrapatellar branch of the saphenous nerve during the standard anterior skin incision. Although peri-incisional numbness is often not regarded as a major complication, it may negatively influence postoperative comfort and patient satisfaction and may also be associated with persistent local pain.
This study was designed to investigate whether a modified J-shaped skin incision could reduce peri-incisional numbness compared with the conventional midline incision in patients undergoing primary TKA. The underlying rationale is that altering the distal course of the skin incision laterally near the tibial tuberosity may help decrease injury to the infrapatellar branch of the saphenous nerve while preserving standard surgical exposure and not increasing operative difficulty or wound-related complications.
In this prospective randomized controlled trial, 62 patients with Kellgren-Lawrence grade 4 varus osteoarthritis scheduled for primary TKA were allocated to one of two groups: a conventional midline incision group or a modified J-shaped incision group. In the modified technique, the distal portion of the incision is curved laterally by approximately 3 cm at the level of the tibial tuberosity. All participants undergo peri-incisional sensory evaluation preoperatively and again at 2 and 6 months postoperatively. Sensory loss is quantified using Semmes-Weinstein 10-g monofilament testing combined with a grid-mapping method to determine the area of numbness.
The primary outcome measure is the area of peri-incisional numbness after surgery. Secondary outcome measures include postoperative pain assessed by visual analog scale (VAS), functional outcomes assessed by The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Hospital for Special Surgery Knee-Rating Scale (HSS) and Anterior Knee Pain Scale (AKPS) scores, range of motion, estimated blood loss, tourniquet time, and wound-related complications. These measures are intended to determine whether the modified incision provides sensory and pain-related benefits without adversely affecting clinical recovery, surgical efficiency, or wound healing.
Based on the study findings summarized in the abstract, the modified J-shaped incision was associated with a significantly smaller area of postoperative numbness at both 2 and 6 months and with lower pain scores at 6 months, while functional scores, range of motion, blood loss, tourniquet time, and wound-related complications were similar between groups. These findings support the hypothesis that a simple modification of the skin incision may improve postoperative sensory outcomes and comfort after primary TKA without increasing surgical risk.
3,292 studies on the registry are indexed under Osteoarthritis, Knee; 623 are open to participants now.
This study's enrollment of 62 is close to the median of 68 across 2,714 interventional studies indexed under Osteoarthritis, Knee.
Browse Osteoarthritis, Knee studies →Fatih Sultan Mehmet Training and Research Hospital is the lead sponsor of 120 studies on the registry; 34 are open to participants now.
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Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants undergo primary total knee arthroplasty using a conventional midline skin incision.
Procedure: Conventional Midline Incision
Participants undergo primary total knee arthroplasty using a modified J-shaped skin incision, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity.
Procedure: J-shaped Incision
A conventional midline skin incision is used during primary total knee arthroplasty.
Also known as: Standard midline incision
A modified J-shaped skin incision is used during primary total knee arthroplasty, in which the distal portion of the incision is curved laterally at the level of the tibial tuberosity.
Also known as: Modified J-shaped incision
Area of peri-incisional sensory loss
The extent of peri-incisional sensory loss will be assessed using Semmes-Weinstein 10-g monofilament testing combined with a standardized grid-mapping method to quantify the area of numbness around the surgical incision.
Time frame: 2 months and 6 months postoperatively
Postoperative pain
Postoperative pain will be assessed using the Visual Analog Scale (VAS) for pain at 2 months and 6 months postoperatively. The VAS ranges from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain. Higher scores indicate worse pain.
Time frame: 2 months and 6 months postoperatively
Range of motion
Knee range of motion will be measured clinically in degrees.
Time frame: 2 months and 6 months postoperatively
Intraoperative Blood Loss
Intraoperative blood loss will be recorded during the surgical procedure. Blood loss will be measured in milliliters (mL). Higher values indicate greater blood loss.
Time frame: Intraoperative period
Tourniquet Time
Tourniquet time will be recorded during the surgical procedure. Tourniquet time will be measured in minutes. Higher values indicate longer tourniquet use.
Time frame: Intraoperative period
Incision Length
Incision length will be measured intraoperatively in centimeters (cm). Higher values indicate a longer skin incision.
Time frame: Intraoperative period
Wound complications
Postoperative wound-related complications will be assessed clinically.
Time frame: Up to 6 months postoperatively
Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) Score
Functional outcome will be assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at 2 months and 6 months postoperatively. If reported on a 0 to 100 scale, 0 indicates the worst symptoms/function and 100 indicates the best symptoms/function. Higher scores indicate better outcome.
Time frame: 2 months and 6 months postoperatively
Knee injury and Osteoarthritis Outcome Score (KOOS)
Functional outcome will be assessed using the Knee injury and Osteoarthritis Outcome Score (KOOS) at 2 months and 6 months postoperatively. KOOS subscale scores range from 0 to 100, where 0 indicates extreme knee problems and 100 indicates no knee problems. Higher scores indicate better outcome.
Time frame: 2 months and 6 months postoperatively
Hospital for Special Surgery (HSS) Knee Score
Functional outcome will be assessed using the Hospital for Special Surgery Knee Score (HSS) at 2 months and 6 months postoperatively. The HSS score ranges from 0 to 100, with higher scores indicating better knee function.
Time frame: 2 months and 6 months postoperatively
Kujala Anterior Knee Pain Scale Score
Functional outcome will be assessed using the Kujala Anterior Knee Pain Scale at 2 months and 6 months postoperatively. The score ranges from 0 to 100, with higher scores indicating better knee function and fewer symptoms.
Time frame: 2 months and 6 months postoperatively
Plan to share: No
This study is completed, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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