Patient Specific Instrumentation (PSI) Referencing Osteotomy Technological Transfer - a Randomized Control Trial (RCT)

Chinese University of Hong Kong40 enrolled

Overview

Medial open wedge high tibial osteotomy is a surgery performed to treat knee osteoarthritis in young patients.Recently with our department advance of technology, the investigators performed computed tomography for the patient's lower limb and 3D reconstruct the image. Based on the 3D image, the investigators planned our planned osteotomy cut on computer software Materialize 3 and the investigators then 3D printed a metal jig that has a slot to produce the osteotomy and also protected the neurovascular bundles. Therefore these metal jigs are specific to each patients. The investigators have performed a few cases of HTO under this extra metal jig protection and guidance and noted it has improved accuracy and safety clinically. However, whether it has scientific significance difference in accuracy is not known.

Medial open wedge high tibial osteotomy is a surgery performed to treat knee osteoarthritis in young patients. Currently the investigators perform high tibial osteotomy under the guidance of computer navigation to achieve the required alignment. During conventional high tibial osteotomy the bone cut is done by free hand cutting, there are risks of cutting into the posterior proximal tibia compartment and transect the neurovascular bundles which is a surgical disaster and may then lead to loss of limb. And the accuracy of free hand cutting is limited by experience of surgeons. In our conventional high tibial osteotomy transection of neurovascular bundles has never happened given our meticulous surgical technique but the investigators believe an extra protection is always beneficial to our patients. Recently with our department advance of technology, the investigators performed computed tomography for the patient's lower limb and 3D reconstruct the image. Based on the 3D image, the investigators planned our planned osteotomy cut on computer software Materialize 3 and the investigators then 3D printed a metal jig that has a slot to produce the osteotomy and also protected the neurovascular bundles. Therefore these metal jigs are specific to each patients. The investigators have performed a few cases of HTO under this extra metal jig protection and guidance and noted it has improved accuracy and safety clinically. However, whether it has scientific significance difference in accuracy is not known.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Interventions

3D printed patient specific metal jigs (PSI jig)PROCEDURE

PSI jig is created based on the pre-operative CT image. Standard medial open wedge osteotomy described previously is performed. Incision is made in the midway between posteromedial border of the tibia and medial aspect of the tibial tuberosity. Sartorius fascia is cut and retracted medially to expose the medial collateral ligament (MCL). Then the PSI jig is positioned onto the tibia. Due to the jig patient specific design (individually based on each patient's CT image), it can fit closely to the proximal tibia. The slot opening on the PSI jig corresponds to 4 cm below the medial joint line and the slot design allow the sawblade cut direction toward the safe zone of the lateral cortex under fluoroscopy. The PSI Jig is removed after the bone cut completed and would not retain in patient's body.

HTO with navigationPROCEDURE

In brief, an incision is made in the midway between posteromedial border of the tibia and medial aspect of the tibial tuberosity. Sartorius fascia is cut and retracted medially to expose the medial collateral ligament (MCL). Two to three K-wires are placed 4 cm below the medial joint line toward the safe zone (an area between the tip of the fibular head and the remnant of fibular head epiphysis line) of the lateral cortex under fluoroscopy and osteotomy is done below and parallel to the k-wires using an oscillating saw leaving the lateral 10 mm intact.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 70 Years

Medical Language ↔ Plain English

Inclusion Criteria: * symptomatic patient with medial compartment knee OA * medial compartment OA was grade 3 or milder according to Kellgren-Lawrence classification Exclusion Criteria: * lateral compartment OA * symptomatic patellofemoral compartment OA, * inflammatory arthritis, * significant loss of knee joint range in flexion (less than 100°) or in extension (less than - 10°), * ligamentous instability, * obesity with a body mass index greater than 30, * significant psychological disorder * inability to communicate in Chinese or English language

Outcomes

Primary Outcomes

Knee Society knee score

Clinical and functional scores, on a 100-point scale; Knee Society score (KSS) has a "Knee Score" section (7 items) and a "Functional Score" section (3 items). Both sections are scored from 0 to 100 with lower scores being indicative of worse knee conditions and higher scores being indicative of better knee conditions. "Excellent" for score 80-100, "Good" for score 70-79, "Fair" for score 60-69, "Poor" for score below 60.

Time frame: 1 week before surgery

Knee Society knee score

Time frame: 6 months post-op

Knee Society knee score

Time frame: 1 year post-op

Knee Society knee score

Time frame: 2 year post-op

Knee Society function score

Time frame: 1 week before surgery

Knee Society function score

Time frame: 6 months post-op

Knee Society function score

Time frame: 1 year post-op

Knee Society function score

Time frame: 2 year post-op

Oxford Knee Score

Clinical and functional scores

Time frame: 1 week before surgery

Oxford Knee Score

Clinical and functional scores

Time frame: 6 months post-op

Oxford Knee Score

Clinical and functional scores

Time frame: 1 year post-op

Oxford Knee Score

Clinical and functional scores

Time frame: 2 year post-op

Range of motion