Knee Osteotomy: Understanding HTO, DFO, and Recovery

What are the different types of osteotomy of the knee?

Knee osteotomy is a surgical procedure that involves cutting and reshaping a bone in the leg (either the tibia or femur) to realign the knee joint, redistribute weight-bearing forces, and alleviate pain, typically used to treat osteoarthritis or correct deformities.

Understanding Knee Osteotomy: A Foundational Overview

Knee osteotomy is a limb-sparing surgical procedure designed to correct the alignment of the knee joint. Its primary purpose is to shift the weight-bearing load from a damaged or arthritic part of the knee to a healthier area, thereby preserving the natural joint and often delaying the need for a total knee replacement. This procedure is commonly considered for younger, active individuals with unicompartmental osteoarthritis (arthritis affecting only one side of the knee) or significant knee deformities that lead to unequal stress distribution across the joint. The goal is to reduce pain, improve function, and slow the progression of arthritis.

High Tibial Osteotomy (HTO)

High Tibial Osteotomy (HTO) is the most common type of knee osteotomy. It involves cutting and reshaping the tibia (shin bone), specifically just below the knee joint. HTO is primarily performed to treat medial compartment osteoarthritis, a condition where the cartilage on the inner (medial) side of the knee is worn away. Individuals with a varus deformity (bow-legged appearance), which places excessive stress on the medial compartment, are often candidates for HTO.

There are two main techniques for HTO:

• Opening-Wedge HTO:

  • Procedure: A cut is made through the medial (inner) side of the tibia, just below the knee. A wedge-shaped gap is then opened and filled with a bone graft (either from the patient, a donor, or synthetic material) or a bone substitute. A plate and screws are used to stabilize the bone while it heals.
  • Purpose: This technique effectively lengthens the medial side of the tibia, shifting the mechanical axis of the leg laterally (outward). This transfers the weight-bearing load from the damaged medial compartment to the healthier lateral (outer) compartment of the knee.
  • Advantages: Less invasive to the fibula, potentially simpler to correct larger deformities.
  • Disadvantages: Requires bone graft, potentially longer non-weight-bearing period, risk of delayed union or non-union.

• Closing-Wedge HTO:

  • Procedure: A wedge-shaped section of bone is removed from the lateral (outer) side of the tibia, just below the knee. The remaining bone ends are then brought together and secured with staples or screws.
  • Purpose: This technique shortens the lateral side of the tibia, shifting the mechanical axis of the leg medially (inward). This transfers the weight-bearing load from the damaged medial compartment to the healthier lateral compartment.
  • Advantages: Does not require bone graft, potentially faster healing due to direct bone-to-bone contact.
  • Disadvantages: Requires fibular osteotomy (cutting the fibula), can result in limb shortening, technically more challenging for some surgeons.

Distal Femoral Osteotomy (DFO)

Distal Femoral Osteotomy (DFO) involves cutting and reshaping the femur (thigh bone), specifically just above the knee joint. DFO is less common than HTO and is primarily performed to address lateral compartment osteoarthritis or a valgus deformity (knock-kneed appearance), where the knee is angled inward, placing excessive stress on the outer (lateral) compartment.

Similar to HTO, DFO can also be performed using opening-wedge or closing-wedge techniques:

• Opening-Wedge DFO:

  • Procedure: A cut is made through the lateral (outer) side of the distal femur. A wedge-shaped gap is opened and filled with a bone graft or substitute, then secured with a plate and screws.
  • Purpose: This effectively lengthens the lateral side of the femur, shifting the mechanical axis of the leg medially (inward). This transfers the weight-bearing load from the damaged lateral compartment to the healthier medial compartment.

• Closing-WFO DFO:

  • Procedure: A wedge-shaped section of bone is removed from the medial (inner) side of the distal femur. The remaining bone ends are then brought together and secured.
  • Purpose: This shortens the medial side of the femur, shifting the mechanical axis of the leg laterally (outward). This transfers the weight-bearing load from the damaged lateral compartment to the healthier medial compartment.

Post-Operative Considerations and Rehabilitation

Regardless of the specific osteotomy type, post-operative care and rehabilitation are critical for a successful outcome. Patients typically experience a period of non-weight-bearing or partial weight-bearing, often requiring crutches or a walker. Physical therapy begins early to restore range of motion, reduce swelling, and gradually build strength.

Key aspects of rehabilitation include:

• Pain Management: Controlled with medication initially, transitioning to non-pharmacological methods.
• Weight-Bearing Restrictions: Strictly followed as prescribed by the surgeon to allow bone healing.
• Range of Motion Exercises: Passive and active exercises to prevent stiffness and restore knee mobility.
• Strengthening: Progressive exercises targeting quadriceps, hamstrings, glutes, and calf muscles.
• Proprioception and Balance Training: Crucial for restoring stability and confidence in movement.
• Activity Progression: Gradual return to daily activities and, eventually, sport-specific movements under professional guidance.

Who is a Candidate for Knee Osteotomy?

Knee osteotomy is not suitable for everyone. Ideal candidates are typically:

• Younger than 60-65 years old: Osteotomy aims to preserve the natural joint, making it more suitable for individuals with a longer expected lifespan for their knee.
• Active individuals: Those who wish to maintain a high level of activity, including sports, which might be challenging after a total knee replacement.
• Unicompartmental Arthritis: Arthritis confined to only one side (medial or lateral) of the knee joint.
• Good Range of Motion: The knee should have good flexibility before surgery.
• Non-Obese: Excessive weight can put undue stress on the healing bone and the realigned joint.

It is often considered an alternative to total knee replacement for suitable candidates, aiming to delay or even avoid the need for a prosthetic joint.

Potential Risks and Benefits

Like any surgical procedure, knee osteotomy carries both potential benefits and risks.

Benefits:

• Pain Relief: Significant reduction in pain from the affected compartment.
• Delaying Total Knee Replacement: Can extend the lifespan of the natural knee joint by many years.
• Preservation of Natural Joint: Maintains the knee's natural motion and proprioception (sense of joint position).
• Improved Function: Allows for a return to higher-impact activities than typically recommended after total knee replacement.

Risks:

• Infection: Risk inherent in any surgery.
• Non-Union or Delayed Union: The bone may not heal properly or may take longer than expected.
• Over- or Under-Correction: The alignment may not be perfectly corrected, potentially requiring further intervention.
• Nerve or Vascular Injury: Rare but possible damage to surrounding structures.
• Blood Clots: Deep vein thrombosis (DVT) or pulmonary embolism (PE).
• Hardware Complications: Irritation or need for removal of plates/screws.
• Compartment Syndrome: A rare but serious condition involving increased pressure in a muscle compartment.

Conclusion

Knee osteotomy, encompassing High Tibial Osteotomy (HTO) and Distal Femoral Osteotomy (DFO) with their respective opening and closing wedge techniques, represents a valuable surgical option for individuals dealing with unicompartmental knee arthritis or significant alignment deformities. By strategically realigning the knee joint and redistributing weight-bearing forces, these procedures can effectively alleviate pain, improve function, and significantly delay the need for total knee replacement, offering a pathway to continued active living for carefully selected candidates. Understanding the specific type of osteotomy and its biomechanical implications is crucial for both patients and fitness professionals supporting their recovery.