- Discussion:
- see:
Oasis Surgical Technique by Jack Farr
- uses a distraction
histiogenesis stratedgy;
- indicated for patients with severe deformities (more than 15 deg varus) where the standard
Coventry osteotomy cannot provide enough correction;
- in the study by G. Magyar et al. (JBJS Vol 81-B May 1999), there was no clinical differences between closed and opening wedge osteotomy;
- the authors found the opening wedge technique technically easy, gave precise results, and was well tolerated by patients;
- in the study by AE Weale et al (CORR 2001 Jan;2001(382):154-167), the authors studied whether opening wedge osteotomy
using hemicallotasis techniques is safer than, and the outcome comparable with that of, conventional techniques;
- 76 high tibial osteotomies were performed in 65 patients for primary osteoarthritis. The mean age of the patients
was 54.8 years (range, 36-70 years);
- mean followup was 6 years;
- only serious complication occurred in one patient, who had chronic osteomyelitis develop 2 years after surgery;
- survivorship at 5 and 10 years was 89% and 63%, respectively;
- advantages:
- fibular osteotomy is not necessary;
- limb is not shortened;
- patellofemoral function is not altered since the osteotomy is below the tubercle;
- disadvantages:
- regenerate bone can be soft and may allow depression (collapse) of the medial compartment;
- patients may be annoyed at having to bear with the fixator for 3 months;
- Technique:
- pins are inserted prior to osteotomy:
- proximal pins:
- two 6/5.0 mm cancellous half pins are placed on medial side of proximal tibia about 2.0 cm below the joint line;
- distal pins:
- three 6/5.0 mm coritcal half pins are placed as close as possible in the medial (coronal plane) which ends up very close to the posterior tibial border;
- osteotomy:
- transverse osteotomy is created through the distal third of the tibial tuberosity using a drill and osteotome technique;
- the incision is longitudinal and is centered over the rotatory hinge of the proximal "T" piece;
-
controversies:
- whether to preserve the lateral 25% of the tibial circumference as a hinge (otherwise, distraction will cause leg lengthening rather than valgus correction);
- in cases of severe internal tibial torsion, it may be necessary to disrupt the lateral cortex inorder to externally rotate the tibia so that
the alignment of the patella to the tibial cortex intersects the second metarsal;
- reference:
The Effect of Lateral Cortex Disruption and Repair on the Stability of the Medial Opening Wedge High Tibial Osteotomy.
- fixation:
- apply a distraction fixator (such as
EBI fixator) w/ proximal "T" configuration;
- leave osteotomy in slight compression for 10 days, before starting to angle the fixator into valgus;
- each day the fixator is angled about 1 degree;
- post operative care:
- fixator is generally left in place for 3 to 4 months;
- Complications:
- pin site infection:
- may range from 18% to 51%;
- there are anectodal reports of patients developing infection after total knee replacements which were performed years after opening wedge
osteotomy which were complicated by pin track infection;
- loss of correction:
- this complication may occur if the fixator is prematurely removed (before 3 months)
- patients should agree in writing to bear with the fixator for the required period of time inorder to achieve a satisfactory correction;
- in the prospective study by G. Magyar et al (JBJS - Br 1999), there were no cases of loss of correction (fixators were left in place for 3 mo);
- references:
-
Complications in high tibial (medial opening wedge) osteotomy
Progressive opening wedge osteotomy for severe tibia vara in adults.
J. de Pablos MD et al.
Orthopedics. Dec 1998. p 1255.
Open-wedge osteotomy by hemicallotasis or the closed wedge technique for osteoarthritis of the knee. A randomized study of 50 operations.
G. Magyar et al.
JBJS. Vol 81-B. No 3. May 1999. p 444.
Hemicallotasis open wedge ostetomy for osteoarthritis of the knee.
Complications in 308 operations.
G. Magyar et al.
JBJS. Vol 81-B. No 3. May 1999. p 449.
High Tibial Osteotomy Using a Dynamic Axial External Fixator
A. E. Weale, MB, BS*; A. S. Lee, MA**; A. G. MacEachern, MB, BS.
Clin Orthop 2001 January;2001(382):154-167
*Opening wedge high tibial osteotomy for symptomatic hyperextension-varus thrust. Am J Sports Med. 2004 Jan-Feb;32(1):60-70.
Greater frequency of distraction accelerates bone formation in open-wedge proximal tibial osteotomy with hemicallotasis.
The Effect of Lateral Cortex Disruption and Repair on the Stability of the Medial Opening Wedge High Tibial Osteotomy.
