High Tibial Osteotomy Surgery

HTO is most commonly performed in  patients younger than 60-65, though it can be performed in older  patients if other factors are favorable. Patients should  understand that HTO delays but may not prevent eventual total  knee replacement in the future. 

High activity level and desire to preserve the natural knee are  important candidate characteristics. Patients should be willing  and able to comply with postoperative restrictions during  healing. Adequate bone quality is necessary for healing of the  osteotomy site. 

Candidates typically have: medial compartment osteoarthritis  confirmed on imaging, significant functional limitation from pain  and dysfunction, failure of conservative treatment to provide  adequate relief, varus (bowleg) malalignment with weight-bearing  axis in the medial compartment, intact or minimally damaged ACL  and PCL, reasonable overall health and bone quality, and  realistic expectations about outcomes. 

Advantages of High Tibial Osteotomy 

The biggest benefit of HTO is that it maintains the patient’s normal knee joint anatomy without replacement of the knee with a prosthesis. Mechanical pain relief by correct alignment may help to slow or stop the progression of arthritis. 

For younger (active) patients, HTO provides the opportunity for ongoing high level activity and sport participation that may not be possible after knee replacement. The natural knee has proprioception. 

Many patients prefer to use (joint position sense) to replaced joints which they find better. 

HTO provides for future treatment options

Later on, it’s in other compartments and total knee replacement remains a possibility. If the HTO is effective at relieving the pain, however, the need for total replacement might not be necessary. 

Successful HTO can offer excellent pain relief and functional improvement for 10-15+ years, to delay or even prevent knee replacement surgery in a patient’s lifetime. 

The Anatomy of Knee Alignment 

The weight bearing axis (line through the center of the hip, knee and ankle when standing) normally goes through the center of the knee joint. This weight-bearing axis will be pushed medially (inwards towards the knee) and will thus focus weight-bearing forces on the arthritic medial  compartment. 

The principle of HTO is to weight shift the axis laterally; to offload a damaged medial compartment onto an intact lateral compartment. This is done by cutting through the tibia below the knee joint and turning the tibia towards the lateral side. 

Usually, alignment is expressed by the mechanical axis (line from centre of hip, through the centre of the knee and on to the centre of the ankle). Normal  alignment has the mechanical axis passing through the center of  the knee. With varus alignment the axis is medial to center.  Successful HTO will lead to an axis that tends to become neutral or even slightly valgus, and the healthy lateral compartment is optimally loaded. 

Preoperative Planning with HTO 

Preparing the teams well for the pre-operations is essential for HTO success. A x-ray is used to see how much malalignment there is, if the compartments are involved and where the mechanical axis is located. Long leg X-rays (hip to the ankle) can be used to check for overall alignment and determine the amount of correction that will be required. 

A scanogram or computed tomography (CT) scan of the area might be taken to evaluate precision alignment. MRI can help with the evaluation of cartilage damage, and the integrity of ligaments and the disease of the meniscus.

The surgeon sets the amount of correction desired, which is usually to position the weight-bearing axis into the lateral  compartment, but not into excessive valgus alignment. The location and orientation of the osteotomy cut is determined by the planning. How the cut is oriented and positioned should be planned to ensure that the desired correction can be made with sufficient retention of bone. 

 The technique of surgery will be either selected plate and screw fixation or external fixation or hybrid external and internal fixation. 

High Tibial Osteotomy Surgical Technique 

General or spinal anesthesia is typically used for HTO.  The patient is supine (on his back), with the surgical leg exposed. Sterile field is set up. 

A skin cut is made in the front of the shin bone (tibia) just below the knee joint. Positioning and protection of saphenous nerve.  The tibia bone is displaying. 

A bone cut (osteotomy) is made in the bone of the upper tibia with a saw and special guides. The cut is determined preoperatively to obtain the  desired mechanical axis correction and its location and orientation are dictated by that. For closing wedge osteotomy,  a wedge of bone is removed. In case of opening wedge osteotomy, the bone gap will be formed and filled with a bone graft. 

The tibia is pushed in line to reposition it. Then it is again verified by using intraoperative imaging (X-rays) taken in different planes, which is used to assess the position of mechanical axis and the overall alignment. 

The osteotomy is fixed in place using internal fixation devices  (plates and screws) or external fixators. Mobilisation of the injured extremity can be achieved early with plates. External fixators allow  adjustment of alignment postoperatively if needed. 

In the case of opening wedge osteotomy, a bone graft (autograft or  allograft) is used to help stabilize the correction and aid in the healing of the bone. Surgical wound is closed layer by layer. 

Advantages and Disadvantages of Different Techniques 

Closing wedge osteotomy: Rids of the problem and provides for rapid and firm union. The bone that is removed offers less biological material for the graft to be taken from. 

healing. It also makes the tibia shorter creating changes in patellar height and sometimes causing patellar tendon problems. This tends to be in the anterior-lateral portion of the tibial plateau. 

Opening wedge osteotomy: Lengthens the tibia and maintains more  bone. This may take longer to heal as it needs a bone graft. If the osteotomy is not stable or if there is the loss of posterior support, there can be lateral laxity of the knee. Can lead to changes in the anterior tibial slope. 

Dome osteotomy: Cutting of the curved bone in the proximal tibia. Not as widely used; needs special placement and securing. 

The choice of technique will be determined by the anatomy, the amount of correction required, the orthopedic  surgeon‘s preference and other factors. Dr. Sanjay Rawat individually chooses the preferred technique in each patient.

Recovery After High Tibial Osteotomy 

Recovery after an HTO will be longer than most arthroscopic procedures, but usually shorter than the recovery time after a TKA.  During immediate postoperative period, pain management is done by giving medications, elevation and icing to reduce swelling and immobilization using brace. 

Usually weight-bearing is limited at first, allowing steps to be taken over a period of weeks as tolerated. Passive range of motion exercises start early to avoid stiffness, while promoting bone healing. Active motion is gradually introduced as healing  progresses. 

The most common problem in early recovery is disruption of the osteotomy site prior to healing.  Proper weight bearing and bracing is necessary. 

The bone osteotomy usually takes 8-12 weeks to heal enough to be able to walk on the prosthesis without pain. This is the stage where weight bearing is slowly introduced and typically, x-rays of the repaired bone might confirm the weight bearing. 

Full functional recovery is expected in 4-6 months, and there is a possibility of improving beyond this time. High level activities can usually be delayed for 6+ months to allow for secure bony union.

Physical Therapy and Rehabilitation 

PT is a critical aspect following HTO. Progressive range of motion, strengthening, gait training and progressive weight bearing are key activity recommendations for the bone healing process. 

Home exercise programmes are done daily. Strengthening techniques focus on strengthening quadriceps muscles, hamstring muscles, calf muscles and hip stabilizers that will all aid the knee during walking and activities. 

Early motion will not stress the healing osteotomy site, but will prevent stiffness. Protection is provided in early healing by bracing. In general, movement will gradually increase with time as the bone heal and weight bearing occurs. 

Return to Activities After HTO! 

Typically at 3-4 months after returning to normal walking when the osteotomy has healed and strength has been regained. More difficult activities will resume when bones heal. 

Walking should be started again at 3-4 months of age. Light jogging or impact exercise is delayed until the bone is united (usually 6+ months). 

Most patients can return to higher level activities, including running, skiing, hiking and sporting events; this may be limited by pain or other factors. 

Long term outcomes from HTO 

HTO has been effective for long-term pain relief and function in the correct patient population, as evidenced by long-term studies. In most studies, success rate is between 70-90% (good or excellent outcomes and relief from pain) at 10-year follow-up. 

Arthritis in the lateral compartment tends to worsen over time with the benefit of the HTO becoming less over time. Most patients will have a good function for 10-15+/ – years after HTO. 

In some patients as the arthritis gets more severe and affects other compartments, conversion to total knee replacement eventually occurs.  But many years 6+ months for full stability may be the time they may require before knee replacement.