Leg re-alignment as a means to avoid knee replacement
A revolutionary treatment alternative for arthritis sufferers
Oliver Schindler, Consultant Orthopaedic Surgeon, Droitwich Knee Clinic

With the increase of sports related knee injuries and the subsequent development of wear and tear, knee arthritis has become extremely common in the middle-aged and older patient group.  Nearly 50% of patients over the age of 65 report arthritic symptoms, whilst 70% present radiographic changes.  Arthritis has already eclipsed heart disease as the leading cause for disability and as the baby boom generation approaches retirement age, these numbers are expected to rise dramatically.

Figure 1 Diminished joint space between femur & tibia on the inside of the knee indicating localised osteoarthritis

Patients with early arthritis often present to the clinician with a subtle bow-leg (varus) or knock-knee (valgus) deformity.  This is due to the fact that in these cases some of the cartilage structures in weight bearing areas between thigh bone (femur) and shin bone (tibia) have worn.  This in turn reduces the height of the affected knee compartment similar to deflating tyres on one side of a car, causing it to be lop-sided.  Such patients frequently complain of activity related pain or discomfort located across the inner joint space.  The clinician has to assess the patient through obtaining a proper history, followed by a thorough clinical examination and appropriate X-rays (radiographs).  A family history should also be obtained as lower extremity deformities may run in families and should be considered habitual if apparent bilaterally.  It is important to rule-out an acute injury to any of the inside structures of the knee e.g. meniscus (shock-absorber cartilage) or ligament tear. In rare cases the patient may be affected by a process called osteonecrosis, a serious condition which is characterised by localised bone death and sudden onset of pain, which, if untreated can lead to a complete collapse of the knee joint.  The specialist is usually able to exclude such problems from normal arthritis through the patient’s history and specific investigations.

Figure 2 Traditional treatment of osteoarthritis with a partial or, as shown here, a total knee joint replacement

The traditional treatment of patients with subtle knee deformities associated with localised osteoarthritis has been a total knee replacement.  It is generally well understood that a joint replacement has a limited life expectancy and that a revision is inevitable at some point.  Additionally, a replaced knee joint may impose limitations upon the patient’s activity level, which is an important factor when considering the patients ability to continue with certain sporting activities or a specific occupation.  For patients in their 40s and 50s a total knee replacement usually requires lifestyle changes, which may be unacceptable for some. 

A new treatment approach has given hope to this group of patients, allowing the knee joint to be preserved rather than replaced.  Conservative measures can help to ameliorate symptoms if the disease is in its infancy.  Lateral shoe wedges or off-loader braces may help to shift the plumb line (mechanical axis) laterally henceforth off-loading the damaged compartment.  Some patients may benefit from an assessment of the knee using a key-hole procedure (arthroscopy), which also allows for the removal of loose particles and smoothing of joint surfaces. With this technique significant amelioration of symptoms of up to 3 years have been observed.  For more advanced cases however, a new surgical procedure has been developed, which is designed to treat the underlying problem of knee malalignment.  It is based on the principle of transferring load to the unaffected compartment of the knee in order to relieve symptoms and slow disease progression.  The alignment of the opposite knee is usually used as a reference and discrepancies vary between 5 to 20 degrees.

Figure 5 Patient during treatment with external fixator on lower leg.  Patients canambulate without restrictions and rarely need walking aids.

Figure 4 Correction of a bow-leg using an external fixator which gradually straightens the leg until the mechanical axis is deemed back in the centre of the knee. Reprinted from: Surgery of the knee, Fourth Edition, 2005  Insall Scott Osteotomy for the Arthritic knee, page 1339 with permission from Elsevier.

To determine the mechanical axis, which is equivalent to the plumb-line of the leg, radiographs showing the entire lower extremity from hip to ankle are required. Specific measurements are performed to calculate the changes in angulation required to correct the apparent leg deformity. 

The procedure to facilitate straightening is called osteotomy and involves cutting of the tibial bone just below the knee joint and the simultaneous application of an external stabilising frame.  A telescopic mechanism housed inside the frame will then allow for gradual extension and correction of the deformity until the correction target is reached.  Adjustments are possible up to three weeks post surgery.  At this point new radiographs are obtained to establish whether full correction has been achieved.  The osteotomy gap gradually fills with new bone which can be observed through radiographs.  The frame is usually removed once bone healing is complete, which on average takes 10 to 12 weeks.  During this period the patient  usually requires no more than a walking stick for ambulation.  The damaged compartment is consequently offloaded, which in principle reduces the progression of surface wear and buys time before joint replacement surgery might be required.

In order to qualify for such a procedure the clinician has to ascertain that osteoarthritic changes are limited to one joint compartment.  Wear in the remaining knee compartments, with all other compartments may lead to disease progression and could potentially hamper the success of such intervention.  In order to judge upon the suitability and correct indication for a realignment procedure, arthroscopic assessment is sometimes required.  The ideal patient for this procedure is between 35 to 65 years of age, with  no substantial limitation in knee range of motion and symptoms limited to a localised area.  However, patients beyond the age of 65 may qualify but need to be assessed individually.

Patients need to understand the aim of the procedure and it may therefore be helpful to provide a simple analogy to the tracking of the

Figure 6 Long leg alignment radiographs showing a patient’s leg before and after correction of a bow leg deformity.

Figure 7 The same patient as Figure 6 before and after treatment

The clinician has the opportunity to recreate some of the lost surface cartilage at the time of the osteotomy.  This is achieved with so-called marrow stimulation techniques (microfracture), a key-hole procedure by which the surgeon drills into the damaged bone to stimulate a healing response.   If such an operation is added to the osteotomy, reduced weight bearing and a specific physiotherapy regime has to be followed for approximately 8 weeks.  Long term investigations of patients who have undergone leg re-alignment surgery have revealed good results in up to 90% after 5 years and in up to 75% at 10 years post surgery.  These results suggest that joint replacement surgery may be postponed for at least 10 years in the majority of patients who have received an osteotomy

Figure 8 A satisfied patient 6 months after the end of the treatment enjoying a family skiing holiday in France.