UNICOMPARTMENTAL KNEE
ARTHROPLASTY
MINIMALLY INVASIVE TECHNIQUE
Frank R. Ebert, MD
Assistant Chief
Department of Orthopædics
The Union Memorial Hospital
Baltimore, Maryland
History
Unicompartmental knee arthroplasties
have been in use since the early 1970’s.
UKA quickly gained popularity, but
soon got a bad reputation, especially in
the USA.
UKA Failures
 Improper
 Poor
indications
surgical technique (no guides)
 Inferior
prosthetic designs in some
cases (e.g. PCA)
UKA Failures cont’d.

Improper Indication
 Inflammatory Arthritis
 Obesity
 Severe Deformity (> 10° Varus/>15° Valgus)
 Active Young Patient
UKA Failures cont’d.

Surgical Technique
 Overcorrection
 Undercorrection
 Patellar Impingement on Femur
 Component Malposition
UKA Failures cont’d.

Prosthetic Design
 6-mm Polyethylene
 Cementless Fixation
UKA results
Some prostheses like the Marmor, St
George Sledge, and the M.G. have
proven good long term results
UKA Results

Swedish Registry 1975 to 1991

93% Survivorship over 16 years
UKA Results

Swedish Registry 1975-1991
 90% Plus Survivorship – Surgeons doing 15 or
more per year.
 70% to 80% Survivorship – Surgeons doing
less than 15 per year.
 Lesson: DO IT RIGHT!
(Technique and Patient Selection)
Advantages UKA

Less invasive surgery

Shorter hospital stay

Better ROM than TKA

More ”normal knee”

Easier revision
”Miniarthrotomy”
John A Repicci
Buffalo USA
Minimally invasive surgery
”Miniarthrotomy”
 Early
mobilisation
 No Transfusion
 Short hospital stay
 Low Morbidity
 Quick rehabilitation
Concerns Repicci II
 Demanding
surgical technique
 No guides - ”free hand surgery”
 Thin tibial component (6 - 7 mm)
 Limited Sizes
 Long term results?
Why Miller - Galante uni?
Proven good / excellent long term
clinical results
 Excellent results (Nilsson & Dahlen, Hyldahl
al.)
 Adequate alignment and resection guides reproducible surgical technique –
no ”free hand surgery”

MG-UNI
98% 10 yr. Survival (loosening or
revision endpoint.)
98% Good or Excellent Results
-Berger, et al. CORR, 1999
Clinical Results – HSS Scores
n=150
n=147
96
n=51
92
59
58
55
Preop
Postop
Berger RA, et al. Clin Orthop Rel Res. 1999;367:50-60.
Argenson JN, et al. 2001 AAOS presentation.
Swienckowski, J. 2001 Poster Osteopathic Specialists Meeting
95
Clinical Results – HSS Scores
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Excellent
Good
Fair
Berger RA, et al. Clin Orthop Rel Res. 1999;367:50-60.
Swienckowski, J. 2001 Poster Osteopathic Specialists Meeting
Clinical Results – Survivorship
10-year
100%
90%
98%
80%
96%
95%
Argenson
Swienckowski
70%
60%
50%
40%
30%
20%
10%
Berger
n=62
n=160
n=187
Clinical Results – Range of
Motion
160
150
140
130
120
128º
110
100
120º
90
Berger
n=51
Argenson
n=147
Randomised study comparing
metal backed and all poly tibia
Hyldahl, Regner, Carlsson, Kärrholm & Weidenhielm 1999
No difference in clinical results
Metal backed or all poly tibia?
Indications
 Medial
OA grade I-III (Ahlbäck) no inflammatory joint disease
 Mild To Moderate Deformity
 Intact ACL (?)
 Minimal Patellofemoral Symptoms
 Age  55 yrs. (?)
Perioperative
 Short
1
spinal with/without duramorph.
gms.Ceflosporin I.V. prior to
tourniquet inflation.
Postoperative

Compression dressing 24 h

Full weight-bearing 4 - 6 h postop

Free flexion / extension

Oral pain killers

DVT prophylaxis for 1 month
SURGICAL
TECHNIQUE
Miniarthrotomy

Flexed knee

Leg stabilizer

0°-120°
“Miniarthrotomy”

Incision 8-10 cm,
medial to patellar
tendon
Miniarthrotomy

Arthrotomy 8-10 cm

T-incision distal to
vastus medialis

Release 2 cm below
joint line
Femoral drilling i.m.
IM guide femur
Distal femoral cut
Distal femoral cut finished
Femur chamfer cuts
Drilling peg holes
Femur - posterior cut
Tibial resection
Tibial resection horizontal cut
Tibial resection sagittal cut
Resection posterior corner femur
Tibial sizing
Tibia - peg holes
Trial reduction, flexion
Trial reduction, extension
Cementation
Closure
THANK YOU
UNION MEMORIAL HOSPITAL
BALTIMORE, MARYLAND
Migration PFC, Sledge
& MG uni
(tibial component)
Nilsson and Dahlen 1997
mm2,5
2
PFC
Sledge
MG uni
1,5
1
0,5
0
0
3
6
12
months