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The following are detailed surgical notes on various knee arthroplasty techniques. For simpler patient information please see Knee Arthroplasty Information and Knee Arthroplasty Surgical Procedure.


TKR – Design and Technique

Technical goals of TKR

  • Restore mechanical axis.
  • Restore joint line.
  • Balance ligaments.
  • Restore Q angle.

Contraindications to TKR

  • Active infection.
  • Incompetent extensor mechanism.
  • Compromised vascular status.
  • Charcot joint (relative).


 Relevant knee anatomy and alignment

Static alignment
Mechanical axis of the lower extremity passes through centre of hip, knee, and ankle.
Mechanical axis of femur and tibia lie on this line.

Anatomical axis lies 5° varus to the mechanical axis.
Thus to cut perpendicular to the mechanical axis of the leg, you must make the distal femoral cut in 5° of valgus (referenced from an IM rod).
This will correspond to a cut 3° varus to the articular surface.

Anatomical axis is parallel to the mechanical axis, which corresponds to the mechanical axis of the lower limb (and the intramedullar canal of the tibia).
Thus referenced from an IM rod, the tibial cut is perpendicular.
This corresponds to a cut 3° valgus to the articular surface.

Patellar groove
This is collinear with the mechanical axis of the lower limb.
This is perpendicular to the epicondylar axis.
65% of force across the knee joint occurs across the medial compartment.

Bone cut referencing
Various landmarks are used to make femoral and tibial bone cuts which result in joint surface articulating perpendicular to the mechanical axis of the lower extremity in both flexion and extension.


In extension:

Distal cut is referenced as above from an intramedullary guide rod.
An intramedullary femoral jig should be used and the alignment confirmed with extramedullary methods if there is uncertainty (for example; unusual femoral bowing or wide intramedullary canal).
A fluted intramedullary rod should be used because it reduces intramedullary pressure, and the entry hole should be overdrilled to 12mm.
The distal cut is 5-7° valgus relative to this intramedullary (anatomical) axis.
Insall uses:
7 degrees of valgus in varus knees
5 degrees of valgus in valgus knees
6 degrees of valgus in non-deformed knees.
Obese patients get a 5 degree cut to avoid rubbing their knees together.
Shorter patients may need an increased valgus cut angle, and taller patients a decreased valgus cut angle.

In flexion:

There are 3 possible landmarks used as references for the posterior cut:

Posterior condyles
Provide excellent referencing provided they are not altered by the disease process.
Cut is made in 3° of ER relative to normal posterior condyles.
They are particularly unreliable in valgus knees (where the wear is primarily from the LFC).

Epicondylar axis
Lies perpendicular to the mechanical axis (thus any cut must be parallel to it).
The lateral epicondyle is the most prominent of the lateral aspect of the distal femur and is just distal to a leash of condylar vessels.
The medial epicondyle is located in the sulcus between the superficial medial collateral ligament and the deep collateral ligament.
Unfortunately it is anatomically inconsistent and hard to determine.
It is used as a reference and is reserved mainly for revision TKR where there is excessive bone loss.

A-P axis (Whiteside’s line)
Defined by a line drawn from the deepest part of the trochlea groove anteriorly to the centre of the intercondylar notch (which in turn is consistent with the lateral fibres of the PCL insertion).
This is an excellent reference corresponding to the mechanical axis, thus the posterior cut needs to be perpendicular to this line.
Whiteside says this is most reliable.
It can be inaccurate in cases of femoral dysplasia or valgus knee.
Use of Whiteside’s line and the epicondylar axis places the femoral component in the desired three degrees of external rotation. If the posterior condyles are used, three degrees of external rotation will have to be added.

In a typical medial OA knee with correct external rotation of the femoral component more medial posterior femoral condyle than lateral condyle will be removed. In a valgus knee posterior erosion of the lateral femoral component may lead to unwitting internal rotation of the femoral component.


Intraemdullary or extramedullar jigging may be used.
There is no proven benefit of either (similar results).
Extramedulary needed if there is significant tibial bowing (present in 2/3 of valgus knees).

Intramedullary guide.

Cut is perpendicular.
Corresponds to 3° valgus to the articular surface.
Cut is parallel to the fibula in the sagittal plane.
In coronal plane jig points to:
Centre of ankle.
Which is more medial than the mid-malleolar distance.
Line of 2nd ray.

Anterior vs. posterior referencing of the femoral cut.

Anterior referencing will lead to variations in the flexion gap.
Posterior referencing may lead to notching.

Femoral bone plug

A femoral bone plug decreases blood loss by 20-25%.

Tibial slope

Increasing the posterior slope of the tibia will:

  • Increase tendency towards anterior tibial translation.
  • Help PCL deficit.
  • Increase the flexion gap.

Saw cuts

Insall feels that slotted capture guides reduce human error, although they make it difficult to see the tip of the saw blade.
Milling frames create the smoothest bone surface and also generates less heat, resulting in less damage to the bony cut surface.

Bone loss

Contained defects
May be filled with Cement, Cement and screws or Graft.

Uncontained defects

For example, medial tibial loss.
Can be reconstituted with the technique of Windsor.
Convert the medial tibial bone loss defect to a flat surface with a saw cut, and then fix a bone off.  Cut to the cut surface with threaded K wires or screws.
This construct should be protected with a stem.

Dynamic alignment.
A varus moment is imparted to the knee during normal gait that is resisted by the LCL, cruciates and ITB.


The routine approach is a medial parapatellar approach.  This should extend distally to 1cm medial to the tibial tubercle (to avoid a scar directly over the tubercle).

Division of the lateral patellofemoral ligament will aid in patellar eversion.

Running a Bristow posteriorly on the medial aspect of the tibia reflecting the medial capsule, deep MCL and semimembranosis will allow greater external rotation and anterior translation of the tibial tubercle, which will in turn improve exposure and patellar eversion, and decrease the risk of patellar tendon avulsion.

The subvastus exposure is designed to avoid violating the extensor mechanism but provides inferior access to the lateral compartment.

A midvastus approach is a compromise to these two approaches.

Difficult exposure

Quadriceps turndown.
Insall says that this is essentially obsolete with no indications for its use.
It is a narrow inverted V incision based distally with the apex in the quadriceps tendon.

Rectus snip.
The incision in the quadriceps tendon is carried laterally and proximally into the vastus lateralis.
The incision can be combined with a lateral retinacular release, with the blood supply to the patella entering via the superior lateral genicular vessels.

Tibial tubercle osteotomy.
Favoured by Whiteside; he emphasises that a large portion of bone, from 3-6cm in length, should be used to promote reliable healing.

Subperiosteal peel.
A useful technique in the ankylosed knee; the entire soft tissue envelope is peeled from the bone and retracted posteriorly, allowing the distal femur to buttonhole forward.


OKU 7 mentions a well matched prospective study where there was no difference in:

  • Surgical time
  • Postoperative pain
  • Analgesic requirements
  • Drain output
  • Postoperative swelling
  • Incidence of wound complications
  • Incidence of DVTs
  • When tourniquet was or was not used.


Serves multiple functions through the flexion-extension arc:

  • Primarily preventing posterior translation of the tibia.
  • Secondary varus, valgus, and rotational stabiliser (when collateral ligaments are deficient).
  • Resists hyperextension when the posterior capsule is deficient.

Composed of 2 bands:

Tight in flexion.

Tight in extension.
It is often tight in the varus knee and stretched in the valgus knee.
When tight the XS femoral rollback is in flexion.
It can be partially released.
This may result in loss of function in A-P stability, whilst maintaining its secondary functions of rotational and varus-valgus stabilisation.
Release with a bony sleeve from the tibia using an osteotome.
If completely defunctioned a more conforming tibial insert can be used to compensate for its action of A-P stability.

PCL retaining vs. substituting prostheses:

Theoretical benefit of retaining PCL – In Practice:

PCL greater range of flexion due to rollback
Effective rollback requires a flat surface which in turn high contact stresses. Thus most poly inserts are curved to improve congruency but also limit rollback
PCL retention lower failure rate due to less stress being transferred to bone cement by A-P translation
10 year survival rates are similar in PCL retaining and sacrificing prostheses.
PCL aids proprioception.
Patients do have a more symmetrical gait, particularly climbing stairs.
PCL retention aids maintainance of the normal joint line.
Less femoral bone resection.
In prostheses substituting the PCL with a cam mechanism, more femoral bone must be resected.

However note:

  • The PCL must be properly tensioned.
  • The PCL is often abnormal in knees requiring TKR thus compromising its normal function.

Indications for PCL substitution

The situations where one should strongly consider using a cruciate substituting prosthesis include:
PCL incompetence.
Post patellectomy – the weakened extensors allow anterior femoral translation more easily.
Inflammatory arthritis which may lead to late PCL rupture (however OKU 7 mentions study of RA patients with 97% 13yrs).

Mechanisms for PCL substitution

Tibial post/femoral cam.
These use a tibial post that engages in a cam on the femur.
This prevents anterior femoral translation and with further flexion produces femoral roll back.  However, if the flexion gap is loose the femur can jump over the tibial post and dislocate.  This generally needs to be reduced under anesthesia.
Highly conforming poly insert, for example, the ‘conforming plus’ poly in the Profix system.

Balancing and releasing issues

Every effort should be made to balance the knee before increasing the constraint in a TKR.
Assessment is made in flexion and extension, with different releases required depending on the specific imbalance present – see ‘Varus knee’ and ‘Valgus knee.’

Coronal plane balancing

General approach:

Remove osteophytes.
Release specific structures based on their function through the flexion arc.

Tight in Flexion                                             Tight in extension
Anterior 1/2 superficial MCL                  Post 1/2 superficial MCL
Medial                                                               PCL (secondary stabiliser)                         Postero-medial capsule
LCL                                                                     LCL
Lateral                                                               Popliteus                                                        Popliteus
Lateral-posterior capsule
Biceps, gastro, PLC

When extreme deformity cannot be balanced with controlled ligament release the options are:

  • Correct and balance to the maximum degree and then brace the knee for about 6 weeks postoperatively.  This is an option only in fixed varus knees
  • Reconstruct the elongated ligament
  • Use a prosthetic device such as a constrained condylar knee that provides for collateral ligament substitution
  • If the femur is being pushed backwards i.e. the tibia is pulled forwards ensure the PCL isn’t too tight and if so release it.
  • Taking more off the posterior aspect of the femur and increasing the posterior slope of the tibia will increase the flexion gap and effectively increase flexion.

Both Guitronich and Cumberland leave their knees fairly loose, particularly in the elderly.

Sagittal plane balancing

The goal of sagittal plane balancing is to obtain equal flexion and extension gaps.
If the gaps are symmetric, then balancing problems lie in the tibia.  If they are asymmetric the balancing problems lie in the femur.


  • Tight in extension and tight in flexion. Implies not enough tibia removed.  Remove more tibia.
  • Tight in extension and OK in flexion.  Implies not enough distal femur removed.  Release posterior capsule and remove more distal femur.  Note that if too much distal femur is removed the knee may become loose in flexion, as the collateral ligaments are relatively too long.  The patient may require a constrained condylar prosthesis in this situation.
  • OK in extension but tight in flexion. Implies not enough posterior femur removed.  Need to take more off posterior femur i.e. downsize.  Can also increase posterior slope of tibia, and release the PCL.  If the anterior tibia lifts off in knee flexion the PCL is too tight.
  • Loose in extension but OK in flexion. Implies too much distal femur removed.  Need to augment distal femur.
  • OK in extension but loose in flexion. Implies too much posterior femur removed.  Need to increase femoral size and use augments or cement in the posterior gap.

Patella Issues


The patella dome should be medialised as much as possible, and be in the proximal part of the patella.
Internal rotation of the tibial tray will externally rotate the tibial tubercle and should be avoided.
Internal rotation or medial translation of the femur will move the trochlea medially and should be avoided.

Note: if the patella appears to be maltracking it is worthwhile releasing the TQ and reassessing the tracking, as around 50% of knees will show an improvement in tracking with the release.

If a lateral release is required, try to preserve the lateral superior geniculate artery, which is located at the musculotendinous junction of vastus lateralis.

Patella baja

This is most commonly seen after HTO.

Techniques to manage this include:

  • Place dome high up on patella then trim off distal patella.
  • Lower joint line by taking more tibia off and augmenting distal femur.
  • Cut off impinging tibial plastic.
  • Proximal displacement osteotomy of tibial tubercle.

Patella clunk syndrome

This is seen in patients with PCL substituting designs.  A fibrous lesion can develop at the proximal pole of the patella which catches in the box of the femur as the knee extends from around 40 degrees of flexion.  It then pops out with a palpable and audible clunk.  Treatment is with open or arthroscopic debridement.

Patella Resurfacing

This is a controversial area.

Absolute indications for resurfacing

Inflammatory arthritis.
Crystal arthropathy.

Relative indications for resurfacing

Patella wear.
RCT in JBJS 2002 Wood et al using MG II prosthesis.
This is a significantly higher incidence of anterior knee pain if patella not resurfaced.
31% knee pain without resurfacing, 16% with resurfacing.
Weight, not BMI was only variable associated with development of anterior knee pain.
RCT in JBJS 2003 by Waters et al using Press Fit Condylar prosthesis at 5 years found 25% rate of anterior knee pain in patients without resurfacing and 5% rate in patients with resurfacing.

The thickness of the patella must be maintained if it is resurfaced.

Minimum acceptable thickness is 10mm.

Wound closure

Wound closure in 90 degrees of flexion resulted in significantly better flexion at one year followup when compared with closure in extension (Emerson).


May be associated with an early improvement in ROM, but there is no significant difference at 1 year, and there is no difference in the rate of MUAs.
CPM is associated with increased anesthetic requirements and increased wound drainage.
If more than 40 degrees, it decreases oxygen tension in the wound.

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The knee is the largest joint in the body and consists of the lower end of the thigh bone (femur), which rotates on the upper end of the shin bone (tibia), along with the knee cap (patella), which slides in a groove on the end of the femur. Large ligaments attach to the femur and tibia to provide stability. The long thigh muscles give the knee strength.

The joint surfaces where these three bones touch are covered with articular cartilage, a smooth substance that cushions the bones and enables them to move easily and smoothly.

All remaining surfaces of the knee are covered by a thin, smooth tissue liner called the synovial membrane. This membrane releases a specialised fluid that lubricates the knee and reduces friction to nearly zero.

In a healthy knee all of these components work in harmony. But disease or injury can disrupt this, resulting in pain, muscle weakness and reduced function.

In an arthritic knee the components no longer function at their optimum level which restricts movement and interferes with day to day activities.


In an arthritic knee the following is often the result:

  • The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis
  • The capsule of the arthritic knee is swollen
  • The joint space is narrowed and irregular in outline; this can be seen in an X-ray image
  • Bone spurs or excessive bone can also build up around the edges of the joint


The combinations of these factors make the arthritic knee stiff and limit activities due to pain or fatigue.

A typical knee replacement replaces the ends of the femur (thigh bone) and tibia (shin bone) with a plastic prosthesis. The patella (knee cap) is usually replaced as well. In a Unicompartmental Knee Replacement only part of the knee joint is replaced. This is done through a smaller incision than would normally be used for a Total Knee Replacement. 

Unicompartmental Knee Replacement surgery is an option for patients with osteoarthritis that is limited to just one part of the knee.

The surgery is performed through a smaller incision than that used in a Total Knee Replacement which means the surgery is not as traumatic to the knee and allows for a quicker recovery time. 


The knee is divided into three major compartments: the medial compartment (the inside part of the knee), the lateral compartment (the outside part) and the patellofemoral compartment (the front of the knee between the kneecap and thighbone).

In a Unicompartmental Knee Replacement only the damaged compartment is replaced with metal and plastic. The remaining healthy cartilage and bone in the rest of the knee is left untouched.

Published in Information
Tuesday, 01 May 2012 00:00

Patellar Malalignment Information

The knee is the largest joint in the body and consists of the lower end of femur (thigh bone) bone, which rotates on the upper end of the tibia (shin bone), and the patella (knee cap), which slides in a groove on the end of the femur. Large ligaments attach to the femur and tibia to provide stability. 

In a healthy knee the patella sits in the femur trochlear groove on the end of the femur.

The way these two bones move against each other is affected by a number of factors. Any injury or deviations from normality in any one of these factors can lead to problems with the way the patella articulates with the femoral trochlea and can result in pain and instability of the knee.

Patellofemoral malalignment can cause pain at the front of the knee (anterior knee pain), which can lead to patellofemoral arthritis. In its more severe forms it  can cause the patella to dislocate.

The medial patellofemoral ligament (MPFL) attaches to the inner side of the patella and the inner side of the end of the femur. It is the primary medial stabiliser of the patella. The role of this rope like ligament is to prevent the knee from lateral dislocation (dislocating to the outer side of the knee) and subluxation, which is a partial dislocation of the joint. With any lateral movement of the patella the MPFL can be injured or torn. After a patella has dislocated once, the MPFL is often ruptured or stretched and is less reliable in preventing the patella dislocating in the future. 


Patella Dislocation

Patella dislocation is typically caused by a direct blow to the knee or a sudden twist of the leg. It occurs when the patella slips out of its normal position in the patellofemoral groove and generally causes intense pain when it occurs along with swelling of the knee.

Patella dislocation is a common injury mainly in young females with joint hyper flexibility, as well as young athletes. 

It used to be a difficult problem to manage, however, there have been many surgical and non-surgical advancements in techniques to treat this condition.


Classification of patellar dislocation:

  • Traumatic: This is where dislocation is a result of trauma, such as direct blow to the knee, a sharp twist of the leg or rapid change of direction. Traumatic dislocations are often the result of sporting injuries.
  • Recurrent: After the patella has dislocated once before there is often damage to the ligaments stabilising the knee causing them to rupture and stretch. Once this has occurred they become less reliable and dislocations are likely to reoccur.
  • Congenital: This is very rare and usually occurs bilateral (both knees) and is associated with other major anomalies (for example, Down’s Syndrome and arthrogryposis). Patients present at birth with a fixed knee flexion, externally rotated tibia and a high patella which is difficult to palpate. Treatment of this condition is difficult and usually needs surgical correction.
  • Habitual: This is a rare condition where the patella dislocates during flexion and relocates during extension without pain and swelling unlike recurrent patellar dislocation. This condition is very difficult to treat and surgery should be avoided where possible.


Traumatic and recurrent patellar dislocations

These two conditions are related and represent the majority of dislocations. A traumatic dislocation will become recurrent in 15-45% of cases. This occurs more in females with a ratio of 2:1. 


Common Causes of Patella Dislocation:

  • Direct blow to the knee
  • Twisting or pivoting injury to the lower leg, such as with rapidly changing direction
  • Powerful muscle contraction and increased quadriceps angle. The quadriceps angle is the angle between the line of pull of the quadriceps and the line of the pull of the patella ligament. The wider this angle, the harder the quadriceps muscle will try to dislocate the patella when it contracts
  • Congential abnormality, such as shallow or malformed joint surfaces
  • Patella Alta, where the patella sits too high in relation to the femoral trochlea


Signs and Symptoms of Patella Dislocation:

  • Patella dislocation to the outer side of the knee causing an obvious deformity. The patella often relocates on its own once the knee is straightened, reversing the deformity. However, damage to the ligament is still sustained
  • Tenderness, swelling and bruising of the knee
  • Severe pain when attempting to move the knee
  • Difficulty moving the knee
  • The feeling the knee is unstable and might give way



It is common that there is intra-articular damage resulting from patella dislocation. A physical examination can reveal instability of the knee but the best current method of identifying patella malalignment and dislocation is by using both plain radiograph and MRI scans in order to reach the appropriate diagnosis. 

MRI scan is very useful especially in the presence of recent dislocation. Many pathological findings can be diagnosed via MRI scan such as:

  • Rupture of the MPFL
  • Joint effusion (fluid such as blood in the joint)
  • Bruising to the medial patellar surface, bruising to the lateral femoral condyle where the patellar dislocated
  • The presence of loose bodies and other soft tissue, such as cartilage damage
Published in Information
Tuesday, 01 May 2012 00:00

Ankle Fracture Information

Ankle fractures are among the most common bone and joint injuries. 

The ankle joint is made up of three bones:

  • Tibia – the shinbone
  • Fibula – smaller bone of the lower leg
  • Talus – a small bone that sits between the calcaneus (the heel bone) and the tibia and fibula


An ankle fracture is a break to one or more of these bones. Ankle fractures range from a simple break in one bone, which may not prevent walking, to multiple fractures that force the ankle joint out of place and may require no weight bearing for several months. The more bones that are broken the more unstable the ankle will become. Depending on the severity of the injury, ligaments that hold the ankle bones and joint in position may also be damaged.


An ankle fracture is classified according to the specific area of the tibia and fibula to which the break occurs. These classifications include:

  • Medial malleolus – inside part of the tibia
  • Posterior malleolus – back part of the tibia
  • Lateral malleolus – bottom end of the fibula

If both the tibia and fibula are broken it is classified as a bimalleolar fracture. If all medial, posterior and lateral malleoli are broken it is a trimalleolar fracture.


Common Causes of Ankle Fractures:

  • Twisting or rotating the ankle side to side
  • Tripping or falling which cause the ankle to roll inwards or outwards
  • Direct and extreme force applied to the joint such as landing on it from a high height
  • Extreme flexing or extending of the joint


Ankle Fracture Symptoms

It can be difficult to differentiate between a severe ankle sprain and a fractured ankle as the pain of both can feel quite similar. A sprained ankle is a result of damage to only the ligaments that support the joint and not the bones themselves.

Common symptoms of a fractured ankle include:

  • Immediate severe pain at the site of the fracture
  • Swelling
  • Bruising
  • Tender to the touch
  • Unable to put weight through the injured foot. However, sometimes it is possible to walk with a less severe break so it is not ideal to rely on weight baring ability as a test of whether the bone is fractured or not
  • Obvious physical deformity, particularly if the joint is dislocated in addition to the fracture 


Compound Ankle Fractures

A compound fracture or open fracture, is an injury that occurs when there is a break in the skin around the broken bone. This is more serious than a simple fracture with a high risk of infection as the fracture site is exposed to outside dirt and bacteria. Although it is often the case, a bone does not necessarily need to break through the skin to be classified as a compound fracture; if the fracture site is exposed at all it is considered a compound fracture.

Compound fractures are treated and stablised with surgery to minimise the risk of an infection developing which can prevent the bone from healing.


Surgical Procedure 

If the fracture has caused the ankle joint to become unstable surgery is recommended as the best course of action.


During the procedure the bone fragments are first reduced (repositioned) into their normal alignment. The bones are then positioned and held together by a plate attached to the outer bone using pins and screws. In some cases a screw or rod inserted into the bone may be used to keep the bone fragments together while they heal.

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Tuesday, 01 May 2012 00:00

High Tibial Osteotomy Information

A tibial osteotomy is a surgical procedure where the tibia is cut to shorten, lengthen or change its alignment.

It is a useful operation used to relieve pain associated with osteoarthritis of the knee particularly where a patient has wear and tear in one side of the knee (typically the inner or medial side).

The goal is to shift the patient's body weight off the damaged area to the other side of the knee, where the cartilage is still healthy. This is achieved by removing a wedge in the top of the tibia from underneath the healthy side of the knee. This changes the alignment of the knee and unloads the damaged/worn section of the knee and allows for the healthier compartment to take the load.

The idea behind this is: osteoarthritis is due to or can result in malalignment of the knee. If the medial side is affected, this can result in varus malalignment or bowed knees. By removing a wedge of bone from the top of the tibia the normal alignment can be restored, which unloads the damaged surface from the extra load. Once the correct alignment has been achieved the osteotomy is stabilised with a plate so it will heal in the correct position.

Tibial osteotomy can be an alternative to knee replacement surgery (knee arthroplasty) particularly for the younger osteoarthritic patient who wants to continue an active lifestyle. There are no activity restrictions following an osteotomy, which allows patients to continue with high impact activities that aren’t recommended after joint replacement surgery.

Knee replacement surgery, no matter how well performed, is not designed for the rigors of a manual working life, or for a young active sporting lifestyle. Osteotomy can be used as an intermediate procedure before total knee replacement is necessary and to delay the need for the procedure. But it can also be a definitive operation for osteoarthritis in some cases.

After a tibial osteotomy a patient can expect significant relief from pain and disability. However, because the arthritis is not “removed” as such, osteotomy doesn’t always provide 100 per cent relief of pain.

In saying that, a patient will typically be able to safely return to work and physical activity after an osteotomy. 

The two most important factors contributing to the success of a tibial osteotomy are the weight of the patient and the angular correction of the surgery. If the two are ideal the outcome is about 70% of patients should not require any major surgery for the next 10 years.

There are potential complications involved with osteotomy surgery. These include wound problems, infection, delayed or incomplete bone healing, injury to major nerve and blood vessels, compartment syndrome, irritation from metal work and fracture into the knee joint. However, the incidence of complication is low. Potential complications following osteotomy surgery tend to be lower than those associated with joint replacement surgery and the complications are usually more easily dealt with compared to potential complications following a knee replacement. 


high tibial osteotomy

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A tibial plateau fracture classification system was developed in order to assess the degree of injury and the appropriate treatment for each type of fracture. Multiple tibial plateau fracture classification systems have been developed but the most widely accepted and used system is the Schatzker Classification System. It consists of six condyle fracture types classified by fracture pattern and fragment anatomy. Each increasing numeric fracture type denotes increasing severity. The severity correlates with the amount of energy and impact applied to the bone at the time of injury.

  • Type I- Split lateral plateau: This is a wedge-shaped pure cleavage fracture and involves a vertical split of the lateral tibial plateau. It is usually the result of a low energy injury in young individuals with normal bone mineralisation. May be caused by a valgus (force pushing the knee inwards) combined with axial loading. It is common to have a lateral tear to the meniscus.

a fracture of the lateral tibial plateau with a simple vertical split and no commonution

  • Type II - Split depression lateral plateau: This is a combined cleavage and compression fracture and involves vertical split of the lateral condyle combined with depression of the adjacent load bearing part of the condyle. Caused by a valgus force (pushing the knee inwards) on an axially loaded limb. This is a low energy injury typically a result of osteoporotic changes in bone and occurs most commonly in older patients. This is the most common classification of tibial plateau fracture.

a fracture of the lateral tibial plateau with a vertical split and commonution

  • Type III - Depression lateral plateau: This is a pure compression fracture of the lateral or central tibial plateau in which the articular surface of the tibial plateau is depressed. Central depressions are more stable than lateral or posterior. This is a low energy injury typically a result of osteoporotic changes in bone. This classification of fracture is extremely rare and can result in joint instability.

a fracture of the lateral tibial plateau with depression in the joint surface

  • Type IV – Medial plateau: This is a medial tibial plateau fracture with a split or depressed component. It is usually the result of a high energy injury and involves a varus force (pushing the knee outwards) with axial loading at the knee. Most commonly associated with neurovascular injury. May represent a reduced knee fracture-dislocation and subsequent ligament injuries are common. 

a fracture of the medial tibial plateau usually associated with a knee dislocation and neuro-vascular compromise

  • Type V - Bicondylar: These fractures consist of a split fracture of the medial and lateral tibial plateau. It is usually the result of a high energy injury with a pure axial load. May also include damage or injury to the anterior cruciate ligament and collateral ligaments. Generally a small amount of metaphyis remains attached to the joint.

a fracture of both medial and lateral tibial plateaus

  • Type VI - Plateau and metaphyseal-diaphyseal dissociation: The main feature of this type of fracture is a transverse subcondylar fracture with dissociation of the metaphysis from the diaphysis. This is a high energy injury involving complex varus and valgus forces. Often these types of fractures are accompanied by extensive soft tissue injuries and risk of compartment syndrome ( a painful condition where pressure within the muscles builds to dangerous levels).

a fracture of both medial and lateral tibial plateaus and tibial metaphysis

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