HTO: Opening Wedge / Infra-tubercle Osteotomy

- Discussion:
    - see: Oasis Surgical Technique by Jack Farr
    - uses a distraction histiogenesis strategy
            - three separate phases: 
                    - latency phase that immediately follows the osteotomy for some duration during which time no mechanical perturbation is applied;
                    - active or distraction phase during which the two bony segments are mechanically separated;
                    - consolidation phase in which active distraction has ended and healing and maturation of the newly formed regenerate bone takes place
            - basic science: (see bone healing)
                    - in contrast to fracture healing (enchondral healing), bone formation with distraction osteogenesis occurs thru intramembranous healing;
                    - ref: Effects of timing of low-intensity pulsed ultrasound on distraction osteogenesis
    - indications:
           - indicated for patients with severe deformities (more than 15 deg varus) where the standard Coventry osteotomy cannot provide enough correction;
    - in the study by Magyar G, et al. (1999), there was no clinical differences between closed and opening wedge osteotomy;
           - authors found the opening wedge technique technically easy, gave precise results, and was well tolerated by patients;
    - in the study by Weale AE, et al (2001), 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.  - 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; 
    - references:
                  - Open-wedge osteotomy by hemicallotasis or the closed wedge technique for osteoarthritis of the knee. A randomised study of 50 operations
                  - High tibial osteotomy using a dynamic axial external fixator.

- Presurgical Considerations:
    - stop smoking
    - check Vit D;

- Surgical 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 posterior tibial border;
    - osteotomy: 
           - surgical approach:
                   - references:
                           - Posteromedial approach to proximal tibia for corticotomy in callus distractions
                           - [Frequency and severity of callus defects. Dorsomedial vs ventrolateral approach for corticotomy in performing callus distraction of tibia]

           - 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 lateral 25% of 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; 
           - distraction is begun at 10 days;
           - one quater turns are carried out 4 times daily until correction is complete;
           - use clinical degree of correction as main measure of correction (center of patella thru tibial tubercle to 2nd metatarsal); 
           - references:
                 - Early full weight bearing is safe in open-wedge high tibial osteotomy
                 - Greater frequency of distraction accelerates bone formation in open-wedge proximal tibial osteotomy with hemicallotasis. 
                 - Effects of timing of low-intensity pulsed ultrasound on distraction osteogenesis
                 - Dose-dependent effect of low-intensity pulsed ultrasound on callus formation during rapid distraction osteogenesis.
                 - The effect of low intensity pulsed ultrasound applied to rabbit tibiae during the consolidation phase of distraction osteogenesis

- 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 Magyar G, et al (1999), there were no cases of loss of correction (fixators were left in place for 3 mo);
    - references:
          - Open-wedge osteotomy by hemicallotasis or the closed wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.
          - Complications in high tibial (medial opening wedge) osteotomy 



Progressive opening wedge osteotomy for severe tibia vara in adults.     

Open-wedge osteotomy by hemicallotasis or the closed wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.

Hemicallotasis open wedge ostetomy for osteoarthritis of the knee. Complications in 308 operations.  

High Tibial Osteotomy Using a Dynamic Axial External Fixator   

Opening wedge high tibial osteotomy for symptomatic hyperextension-varus thrust. Am J Sports Med. 2004 Jan-Feb;32(1):60-70.  

The Effect of Lateral Cortex Disruption and Repair on the Stability of the Medial Opening Wedge High Tibial Osteotomy. 

Osteotomies around the knee: patient selection, stability of fixation and bone healing in high tibial osteotomies.

 




Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, February 19, 2013 9:50 pm