Knee Arthritis
Conditions
Keywords
Total Knee Arthroplasty, Instrumentation
Brief summary
The main purpose of this study is to determine whether the surgical time required for primary total knee arthroplasty is significantly less when performed with Customized Patient Instrumentation (CPI) than with conventional instrumentation. Each case will be recorded by video camera, in order to time the length of surgery and each surgical step. The number of surgical trays required for each case will be recorded. As an additional endpoint, the investigators will measure limb and component alignment on x-rays to determine if these two methods achieve equivalent alignment results. The thickness of bone cuts will be compared to the surgical plan and to each other. The primary hypothesis is that the use of customized patient instrumentation will reduce the operative time required for total knee arthroplasty.
Detailed description
Patient-specific instrumentation (PSI) has been developed for total knee arthroplasty (TKA) with several potential advantages over traditional instrumentation (TI). Shortened surgical time, fewer surgical instruments, and improved alignment are some of these proposed advantages. We sought to examine these assertions. 52 patients (26 per group) were enrolled in a prospective, randomized trial comparing CT-based PSI with TI. No difference was seen in average patient age (68 years) or BMI (31) between groups (p=0.84 and p=0.89), although there were more males in the PSI group (14 vs 7, p=0.002). A single surgeon and consistent staff performed the surgeries with the same knee prostheses, and all cases were videotaped to measure the length of surgery and each individual step. Any additional bone cuts, size changes, or ligament releases made to achieve correct alignment and balance were documented. The number of instrument trays opened for each case was recorded. Postoperative long alignment and lateral radiographs were taken to measure the coronal and sagittal plane component alignment and mechanical axis in each patient.
Interventions
DEVICECustomized Patient Instrumentation
Custom cutting guides based on computed tomography (CT) images of the patient's leg are used to make the bone cuts and select the implant size.
DEVICETraditional Instrumentation
Traditional surgical instruments will be used to make bone cuts and size the components in this control group.
Sponsors
Anderson Orthopaedic Research Institute
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Healthy volunteers
No
Inclusion criteria
* Patient requires unilateral primary total knee arthroplasty
Exclusion criteria
* Body mass index greater than 41 * Previous ipsilateral hip or ankle replacement * Knee flexion contracture greater than 20 degrees
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Length of Surgery | 1 day | Time elapsed from skin incision to wound closure (in seconds) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Length of Each Surgical Step (in Seconds) | 1 day | surgical exposure, tibial alignment and resection, femoral distal cut, extension gap balancing, sizing the femur, 4 finishing femoral cuts, posterior releases, patellar resection, trial components, tibial tray preparation, cleanup/ prep for cement, cementing femur, cementing tibia, cementing patella, and closure |
| Number of Instrument Trays Required | 1 day | — |
| Limb Alignment (Mechanical Axis) | 4 months | Alignment is measured on 4 month postoperative radiograph in degrees. The goal is a mechanical axis between and femur and tibia of 0 degrees. Varus alignment (bow-legged) is shown as a negative number in degrees away from 0. Valgus alignment (Knock-kneed) is expressed as a positive number in degrees away from 0. |
Countries
United States
Participant flow
Recruitment details
Patients were recruited at a suburban orthopaedic clinic setting between June 2010 and Sept 2011.
Pre-assignment details
Patients were excluded if their medical insurance did not cover a leg CT scan or if there was any metal in their leg.
Participants by arm
| Arm | Count |
|---|---|
| Traditional Instrumentation Control group: Cases performed with traditional surgical instruments | 34 |
| Customized Patient Instrumentation Experimental group: Cases performed with custom instruments specifically made for each patient using pre-op CT scans. | 36 |
| Total | 70 |
Baseline characteristics
| Characteristic | Customized Patient Instrumentation | Traditional Instrumentation | Total |
|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 25 Participants | 23 Participants | 48 Participants |
| Age, Categorical Between 18 and 65 years | 11 Participants | 11 Participants | 22 Participants |
| Age, Continuous | 69.2 years STANDARD_DEVIATION 8.5 | 71.3 years STANDARD_DEVIATION 12.1 | 70.1 years STANDARD_DEVIATION 10 |
| Region of Enrollment United States | 36 participants | 34 participants | 70 participants |
| Sex: Female, Male Female | 19 Participants | 23 Participants | 42 Participants |
| Sex: Female, Male Male | 17 Participants | 11 Participants | 28 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | — / — | — / — |
| other Total, other adverse events | 1 / 26 | 0 / 26 |
| serious Total, serious adverse events | 0 / 26 | 0 / 26 |
Outcome results
Primary
Length of Surgery
Time elapsed from skin incision to wound closure (in seconds)
Time frame: 1 day
Population: per protocol
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Traditional Instrumentation | Length of Surgery | 3447.19 seconds | Standard Deviation 297.68 |
| Customized Patient Instrumentation | Length of Surgery | 3707.19 seconds | Standard Deviation 348.26 |
Secondary
Length of Each Surgical Step (in Seconds)
surgical exposure, tibial alignment and resection, femoral distal cut, extension gap balancing, sizing the femur, 4 finishing femoral cuts, posterior releases, patellar resection, trial components, tibial tray preparation, cleanup/ prep for cement, cementing femur, cementing tibia, cementing patella, and closure
Time frame: 1 day
Population: per protocol
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Femoral Distal Cut | 95.19 seconds | Standard Deviation 19.5 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Patellar Resection | 133.04 seconds | Standard Deviation 27.51 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Closure | 1221.62 seconds | Standard Deviation 140.27 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Trial Components | 247.92 seconds | Standard Deviation 64.76 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Extension Gap Balancing | 89.77 seconds | Standard Deviation 73.88 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Tibial Tray Preparation | 71.85 seconds | Standard Deviation 24.2 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Exposure | 297.19 seconds | Standard Deviation 54.87 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Cleanup/ Prepare for Cement | 206.46 seconds | Standard Deviation 59.32 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Sizing the Femur | 41.58 seconds | Standard Deviation 11.7 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Femur | 127.15 seconds | Standard Deviation 22.86 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Tibial Alignment and Resection | 111.77 seconds | Standard Deviation 37.67 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Tibia | 77.77 seconds | Standard Deviation 16.99 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | 4 Finishing Femoral Cuts | 135.54 seconds | Standard Deviation 35.67 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Patella | 102.65 seconds | Standard Deviation 45.14 |
| Traditional Instrumentation | Length of Each Surgical Step (in Seconds) | Posterior Releases | 225.42 seconds | Standard Deviation 46.91 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Closure | 1246.69 seconds | Standard Deviation 133.82 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Tibial Alignment and Resection | 129.73 seconds | Standard Deviation 29.47 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Femoral Distal Cut | 170.46 seconds | Standard Deviation 86.91 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Extension Gap Balancing | 77.88 seconds | Standard Deviation 59.35 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Sizing the Femur | 21.46 seconds | Standard Deviation 42.01 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | 4 Finishing Femoral Cuts | 186.96 seconds | Standard Deviation 89.69 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Posterior Releases | 223.81 seconds | Standard Deviation 51.68 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Patellar Resection | 136.31 seconds | Standard Deviation 30.41 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Trial Components | 253.42 seconds | Standard Deviation 78.78 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Tibial Tray Preparation | 67.54 seconds | Standard Deviation 24.38 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Cleanup/ Prepare for Cement | 196.00 seconds | Standard Deviation 53.16 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Femur | 141.65 seconds | Standard Deviation 22.55 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Tibia | 83.62 seconds | Standard Deviation 18.47 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Cementing Patella | 97.77 seconds | Standard Deviation 22.98 |
| Customized Patient Instrumentation | Length of Each Surgical Step (in Seconds) | Exposure | 318.38 seconds | Standard Deviation 64 |
Secondary
Limb Alignment (Mechanical Axis)
Alignment is measured on 4 month postoperative radiograph in degrees. The goal is a mechanical axis between and femur and tibia of 0 degrees. Varus alignment (bow-legged) is shown as a negative number in degrees away from 0. Valgus alignment (Knock-kneed) is expressed as a positive number in degrees away from 0.
Time frame: 4 months
Population: All participants were x-rayed postoperatively to measure the mechanical axis of the leg in degrees.
| Arm | Measure | Value (MEAN) |
|---|---|---|
| Traditional Instrumentation | Limb Alignment (Mechanical Axis) | 0.7 degrees varus(-) or valgus(+) |
| Customized Patient Instrumentation | Limb Alignment (Mechanical Axis) | 0.3 degrees varus(-) or valgus(+) |
Secondary
Number of Instrument Trays Required
Time frame: 1 day
Population: per protocol
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Traditional Instrumentation | Number of Instrument Trays Required | 7.3 number of trays | Standard Deviation 0.69 |
| Customized Patient Instrumentation | Number of Instrument Trays Required | 2.5 number of trays | Standard Deviation 1.14 |