PATIENT SPECIFIC TECHNOLOGY

*Note: patient specific implants (femoral and tibial components) were not addressed in this review of the literature.

There are inconsistencies in high quality studies with respect to patient outcomes with the majority of studies showing no difference between patient specific and standard instrumentation. Six high quality studies for the KSS (Yan 2015, Schotanus 2019, Abane 2015, Boonen 2016, Stolarczyk 2018, Kosse 2018), six high quality studies for the OKS (Yan 2015, Turgeon 2019, Abane 2018, Abane 2015, Huijbregts 2016, Boonen 2016), four high quality studies for EG-5D VAS (Schotanus 2019, Teeter 2019, Van Leeuwen 2017, Boonen 2016), two high quality studies for EG-5D (Schotanus 2019, Boonen 2016), and three high quality studies showed no difference in VAS Satisfaction (Turgeon 2019, Kosse 2018, Kotela 2015). The study with the longest follow up of 5 years showed no significant differences in survival or patient outcomes between patient specific and standard instrumentation (Schotanus 2019).

With respect to patient function and pain, there were multiple high quality studies that also showed no difference between patient specific and standard instrumentation. Seven high quality studies for KSS Function (Yan 2015, Teeter 2019, Abane 2018, Abane 2015, Maus 2018, Stolarczyk 2018, Kosse 2018), three high quality studies for UCLA activity score (Turgeon 2019, Teeter 2019, Kosse 2018), two high quality studies for SF-12 Physical (Teeter 2019, Huijbregts 2016), and two high quality studies for KOOS ADL and KOOS Symptoms (Van Leeuwen 2017, Kosse 2018), and there was also no difference in ROM (Yan 2015, Sun 2020, Van Leeuwen 2017). Multiple high-quality studies did not support the use of patient specific instrumentation to improve pain with six high quality studies for VAS (Schotanus 2019, Turgeon 2019, Boonen 2016, Stolarczyk 2018, Kosse 2018, Kotela 2015) showing no difference compared to standard instrumentation.

There were multiple inconsistencies in the studies that analyzed operative time comparing patient specific to standard instrumentation. Six high quality studies showed no difference (Yan 2015, Turgeon 2019, Van Leeuwen 2017, Huijbregts 2016, Silva 2020, Maus 2018), four high quality studies favored standard instrumentation (Teeter 2019, Sun 2020, Stolarczyk 2018, Roh 2013), and three high quality studies favored patient specific instrumentation (Boonen 2013, Pfitzner 2014, Vide 2017).

The reporting and results for blood loss were heterogenous and inconsistent with studies using blood transfusion, hemoglobin, and blood loss. One high quality study (Vide 2017) was in favor of patient specific technology and two high quality studies showed no difference (Silva 2020, Kotela 2015) for blood transfusion. Two high quality studies showed no difference (Van Leeuwen 2017, Vide 2017) and one high quality study was in favor of standard technology (Silva 2020) for hemoglobin levels. Two high quality studies showed no difference (Stolarczyk 2018, Kotela 2015) and one high quality study was in favor of patient specific technology (Sun 2020) for blood loss.

There is strong evidence to support patient specific instrumentation does not affect length of stay or complications. Five high quality studies showed no difference compared to conventional instrumentation (Turgeon 2019, Van Leeuwen 2017, Silva 2020, Maus 2018, Kotela 2015). There is strong evidence to support no difference in total revisions, infection, and manipulation under anesthesia (MUA) for patient specific versus standard instrumentation; two high quality studies for total revisions (Schotanus 2019, Boonen 2016), three high quality studies for infection (Huijbregts 2016, Silva 2020, Boonen 2016), and two high quality studies for MUA (Huijbregts 2016, Boonen 2016). 

*KSS = Knee Society Score, OKS = Oxford Knee Score, WOMAC = Western Ontario and McMaster University osteoarthritis Index, EG-5D = EuroQol, VAS = visual analogue score, UCLA = University of California and Los Angeles, KOOS = Knee injury and Osteoarthritis Outcome Score, ROM = range of motion

Benefits/ Harms of Implementation

Proposed benefits of patient specific instrumentation lie in improved accuracy of alignment which could benefit long-term outcomes as malalignment of components is a known major cause of failure and revision. Patient specific instrumentation is useful for rare circumstances when intramedullary instrumentation cannot be utilized. Radiation from CT scan is a potential harm with using patient specific instrumentation.

Outcome Importance

The use of patient specific instrumentation does not improve outcomes, but anecdotally outcomes may be better for surgeons who use it routinely instead of standard instrumentation.

Cost Effectiveness / Resource Utilization

Patient specific instrumentation requires increased cost for hardware/software and advanced imaging (MRI or CT). Seldomly, the MRI may not pass the manufacturer’s protocol rendering the study unusable. Template planning and fabrication takes extra time for the patient specific instrumentation that may decrease its usefulness. Conversely, potential cost savings could exist if its use reduces instruments and sterilization costs, reduced processing, and reduction in hospital storage of implants.

Acceptability

A small number of surgeons continue to use patient specific instrumentation. Those who are accustomed to using them, may find these results unacceptable and will continue to use them.

Feasibility

It is feasible to abandon patient specific instrumentation technology, however some surgeons who still use it in their workflow may find it difficult to return to standard instrumentation.

Future Research

Future research should focus on reduction of outliers in alignment and the long-term effects of patient specific versus conventional instrumentation. Additionally, large studies comparing patient specific to conventional off-the-shelf implants would be beneficial.