of the Unicompartmental Knee Arthroplasty


Fig. 1.1

(MacIntosh tibial insert ) [17]. (MacIntosh tibial insert thicknesses ) [17]


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Fig. 1.2

(a) St. Georg sled in the all-polyethylene tibia version ; (b) Additional version of the St. Georg sled in a coated version for patients with cobalt, chromium, or nickel allergy. This is also available in standard cobalt–chromium components as well.—Courtesy, Link, Hamburg, Germany



Both MacIntosh and McKeever reported positive results, but neither’s results could be replicated consistently enough to be deemed successful. In 1972, MacIntosh published his results and saw an 80% success rate for osteoarthritic knees and only a 69% success rate for rheumatoid knees (Table 1.1;I). Early historical reports of UKA survivorship exhibited varying degrees of success, resulting in many surgeons abandoning the procedure as a treatment for isolated compartmental joint arthritis.


Table 1.1

UKA Prosthesis-specific design survivorship % based on implant failures resulting in revision surgery at time of study reported follow-up





























































Historical UKA prosthesis design survivorship overview


Study


(years)


Prosthesis design


n


Survivorship (%)


Follow-up (years)


I. MacIntosh et al (1972) [17].


MacIntosh vitallum


130


95


7


II. Mackinnon and Mamor et al. (1988) [18].


St. Georg Sled


39


95


90


5


25


III. Kozinn and Scott et al. (1989, 1991) [13, 27].


Unicondylar knee


100


90


83


82


9


10


11


IV. Squire and Callaghan et al. (1998) [31].


Marmor knee


140


84


22


V. Murray et al. (1998) [20].


Oxford Phase 1 and 2


143


98


10


VI. Pandit et al. (2006) [23].


Oxford Phase 3


547


97


96


5


10


VII. Berger and Naudie et al. (2005) [4].


Miller–Galante


62


98


96


10


13


Historically, selection criteria for UKA were nonexistent, and no official consensus was available to guide surgeons. Essentially, there were believers and nonbelievers in the procedure, with no definitive algorithms available for determining appropriate candidates. Kozin and Scott developed the first widely adopted set of indications and contraindications for UKA in the late 1980s. Such criteria were held steadfast until recently, when there has been a challenge to expand the indications for UKA. While some surgeons may now recommend UKA in patients with ACL-deficient knees or patellofemoral arthritis , there remains relatively strong opposition that ascribes to the stricter indications outlined by Kozin and Scott et al. (Table 1.2) [13]. Following these relatively stringent parameters, Ritter et al. found that 4.3% out of 4021 knee arthroplasties met the indications for UKA, while 6.1% were appropriate candidates for UKA based on surgical pathology assessments [25]. These numbers are relatively consistent with current rates of UKA in the United States; however, there are centers driving these numbers up with rates as high as 20–30%.


Table 1.2

Classic indications for UKA outlined by Kozinn and Scott , suggesting the ideal patient should be selected using the following inclusion criteria. Many surgeons still follow these classic indications with extended measures applied to age, weight, and level of activity

































Classic indications for UKA


Study


Proposed UKA selection criteria


Kozinn and Scott et al. (1989) [13]


I. Isolated medial compartment disease


VI. Cumulative angular deformity less than 15°


Indications


II. 60 years age or less


VI. Preoperative range of flexion of at least 90°

 

III. Low level of physical activity


VII. Both cruciate ligaments intact

 

IV. Weight less than 82 kg


VIII. Flexion Contracture less than 5°


Contraindications


Inflammatory arthritis, age less than 60, high activity level, pain at rest, patellofemoral pain, opposite compartment pain, exposed bone in PF compartment


UKA Historical Advancements and Innovation


After the initial introduction of UKA prostheses, modern changes to the implants and refined surgical techniques soon followed and have continued to develop over time. In 1969, the St. Georg Sled (Fig. 1.2) was developed in Hamburg, Germany, as a new cemented UKA option. It built upon the flat polyethylene tibial components used in earlier prosthetic prototypes and added a biometallic biconvex femoral component with two pegs for stability. This fixed-bearing prosthesis reported high levels of survivorship reported out to 25 years (Tables 1.1 and 1.3). At roughly the same time, Gunston and other polycentric knee replacement implants were being developed and brought to market.
Oct 22, 2020 | Posted by in ORTHOPEDIC | Comments Off on of the Unicompartmental Knee Arthroplasty
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