2013 Highlights “Balancing the Hype”: Total Knee Arthroplasty

2013 Highlights "Balancing the Hype": Total Knee Arthroplasty

Papers from 2013 American Academy of Orthopedic Surgeons (AAOS)

Computer Assisted Surgery (CAS)

"Do We Need Computer-Assisted Surgery to Improve the Survival of Total Knee Arthroplasty?-Results at 10.8 yrs"

Kim M.D. et al

Conclusion: Our data demonstrated that CAS THA did not improve the clinical function, alignment, and survivorship of the components compared with conventional TKA

"High Flexion" Total Knee designs

"Prospective Comparison of Mid term Results Between High Flexion and Standard Designs in Cruciate Retaining TKA"

Seon M.D. et al

Conclusion: With a minimum of five year follow up, the High Flexion CR design was found to have no advantages over the standard CR design regarding clinical outcomes.

Unicompartmental Knee Replacement

"Revision Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty: Not Always a Slam Dunk"

Kassel M.D. et al

Average time to revision of the Uni was about 5.5 yrs. Main reasons for failure were loosening 65.1 %,progressive arthritis 30.2 %. After Revision of the Uni to TKA, , the failure rate was 4.7 % at 4.66 yrs.

Conclusion: The re-revision rate after TKA from UKA was 4.7 % at just over four yrs in this series. The survivorship of a revised UKA to TKA is less than a primary TKA and should be considered comparable to a RevisionTKA. ( Some proponents of Unicompartmental Knee Replacements may imply that the results of revising a Uni are similar to a first time Total Knee Replacement. In this study, the results of revising a Uni is similar to the Revision a standard TKA)

"Oxford Unicompartmental Knee Fails at High Rate in a High-Volume Practice"

Schroer M.D. et al

A high early failure rate at 12 % was found, even in the hands of an experienced surgeon." This failure rate has diminished the use of the Oxford knee in this practice."

"Revision of UKA: Is there a Difference Compared to Primary TKA and Revision TKA"

Parratte M.D. et al

"Our results show that function and Quality of life scores after Revision of UKA are lower than Primary TKA and comparable to those observed after Revision TKA. Technically the Revision UKA is less complex, than Revision TKA, but the rate of complication is comparable. UKA is a bone preserving technique, but surgeons cannot advocate that the results of Revision UKA will be as good as a Primary TKA."

Patient specific Instrumentation (PSI)

" Patient Specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty"

Dujardin M.D. et al

"Patient specific instrumentation did not improve accuracy of the coronal, sagittal or axial alignment of the prosthetic components when compared to conventional instrumentation in TKA. Moreover, a significant amount of patient specific guides had to be abandoned because of inaccurate alignment (11.5%)."

Conclusion: 'PSI are heavily promoted by several implant manufacturers who claim better accuracy with use of these devices. The results of this study do not support this claim.'

"Patient Specific Instrumentation Does Not Shorten Surgical Time: A Prospective, Randomized Trial"

Hamilton M.D. et al

Conclusion: "PSI did not shorten surgical time or improve alignment compared with traditional instrumentation in this prospective randomized trial."

"Can MRI-based and CT- based Patient Specific Instruments Deliver their Proposed Advantages?"

Chen MBBS and Foo M.D. et al

"Blind acceptance of the PSI guided TKA is not advisable and we cannot justify its additional cost and waiting time before surgery."

"Patient specific Total Knee Instruments"

C. Anderson Engh M.D.

"With registries (data results of standard TKA studies) showing overall revision rates below 5% after 7-9 yrs, it will take many yrs to prove reduced revision rates. (as data accumulates with studies of PSI use) Similarly, it is a given the technology is more expensive… However, staff realizes that some cases will require traditional instrumentation when the blocks do not fit well…The current literature has limitations, including that it is short term, retrospective, single center and company specific."

Symposium: "Patient Specific Instruments for Total Knee Arthroplasty NOT ready for Prime Time: Affirmative"

Lachiewicz M.D.

Excerpts:

"The supposed advantages of these instruments include more accurate coronal alignment, fewer outliers, no instrumentation of the intramedullary canal, decreased operative time, decreased hospital costs to clean instruments, better outcomes and fewer revisions. However, there is little evidence to support any of these marketing claims. PSI will NOT: perform ligament releases to balance the knee, determine proper tibial component rotation, resect the patella, or cement the components."

"There are many disadvantages of PSI including: cost added approx $1000 for MRI and $1500 for instrumentation, delayed pre op scheduling time, learning curve for surgeon to work with implant company engineers, and uncalculated surgeon planning time.

"A Markov model study reported an increased cost of $4600 for 4.6 Quality Adjusted Life Years (QALYs) for PSI, and the rate of revision must be reduced by 50% or more for these instruments to be cost-effective. The author continues to recommend conventional instruments…There is little evidence to support the claims made by the manufacturers of these PSI or implants."