Intelligent Precision Knee Preservation System for Knee Osteoarthritis

Relative ΔKAM (%) = [(KAM_follow-up - KAM_preoperative) / KAM_preoperative] × 100%

HKA accuracy is defined as the proportion of operated knees whose hip-knee-ankle (HKA) angle falls within the prespecified target window (±2°) on full-length, weight-bearing radiographs at 12 months postoperatively.

Knee Injury and Osteoarthritis Outcome Score (KOOS) is a self-administered questionnaire (paper or electronic; 1-week recall) with 42 items across five subscales: Symptoms, Pain, Activities of Daily Living (ADL), Sport and Recreation Function (Sport/Rec), and Knee-related Quality of Life (QOL). Items are rated 0-4. For each subscale, raw scores are summed and transformed to a 0-100 scale using:

Score = 100 - [(sum of item scores × 100) ÷ (4 × number of items)]. Minimum = 0 (worst outcome); Maximum = 100 (best outcome); higher scores indicate better status.

Subscales are reported separately. If reported, "KOOS4" is the mean of Pain, Symptoms, Sport/Rec, and QOL, also on a 0-100 scale with 0 = worst and 100 = best (higher = better).

The Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index is a self-administered questionnaire designed to assess pain, stiffness, and physical function in patients with hip and knee osteoarthritis. It contains 24 items across three subscales: pain (5 items), stiffness (2 items), and physical function (17 items). Each item is scored on a Likert scale (0-4; none to extreme) or sometimes a 100-mm visual analogue scale, depending on the version used. Scores are summed for each subscale and can be normalized to a 0-100 scale (higher scores indicate worse symptoms).

The Hospital for Special Surgery (HSS) score is a clinician-administered questionnaire designed to evaluate knee function. It includes six domains: pain (30 points), function (22 points), range of motion (18 points), muscle strength (10 points), flexion deformity (10 points), and instability (10 points), with deductions for the use of walking aids. The maximum score is 100 points, with higher scores indicating better knee function: >85 excellent, 70-84 good, 60-69 fair, and <60 poor.

The Lysholm score is a patient-reported outcome measure originally designed for knee ligament injuries, widely used to evaluate knee symptoms and function. It consists of 8 items: limp, need for support, locking, instability, pain, swelling, stair climbing, and squatting. Each item is assigned a weighted point value, and the total score ranges from 0 to 100, with higher scores indicating better knee function. Scores are commonly interpreted as: 95-100 excellent, 84-94 good, 65-83 fair, and <65 poor.

Minimal Clinically Important Difference (MCID) achievement rate :

• For the target outcome, compute each participant's change from baseline to follow-up, signed so that improvement is positive (e.g., Δᵢ = Follow-up - Baseline for "higher=better"; Δᵢ = Baseline - Follow-up for "higher=worse").
• Mark a responder if Δᵢ ≥ MCID (or if using percent MCID: Δ%ᵢ = Δᵢ / Baseline × 100 ≥ MCID%).
• MCID achievement rate (%) = (number of responders ÷ number analyzed at that time point) × 100.

Operative time is calculated as the interval from the first skin incision to completion of skin closure, recorded in minutes from the operating-room record.

The total count of discrete single-image X-ray exposures acquired on the patient from first skin incision to completion of skin closure, as recorded by the C-arm exposure log/PACS.

The proportion of patients requiring reoperation within 12 months of follow-up due to mechanical failure, fracture, or implant-related issues