Dr TK Ho in Surgery

Total Shoulder Replacement

  • 1) What is a Total Shoulder Replacement ? Open or Close

    The shoulder joint mainly consists of a ball and socket, not unlike a hip joint. The socket is part of the shoulder blade or the scapula. The ball sits at the top of the arm bone or humerus. When arthritis has damaged or destroyed the shoulder joint, it may be replaced with an artificial ball and socket. Total shoulder replacement is similar in concept to total hip replacement. When this is performed, the ball is removed from the top of the humerus and replaced with a metal implant. This is shaped like a half-moon and attached to a stem, which is inserted down the center of the arm bone. The socket portion of the joint is shaved clean and replaced with a plastic socket that is cemented into the shoulder blade.

    Fig 1: Total Shoulder Replacement

  • 2) Who may benefit from a Total Shoulder Replacement ? Open or Close

    While shoulder pain is quite common, primary osteoarthritis of the shoulder joint itself is rather uncommon by comparison to other shoulder conditions, such as rotator cuff tears. Therefore a total shoulder replacement operation is not frequently required. In patients with mild or early osteoarthritis, conservative treatment such as activity modification, gentle physical therapy to maintain muscle tone, anti-inflammatory medication and occasional pain medication may be sufficient to make symptoms tolerable. However in patients with severe osteoarthritis where pain, restriction of shoulder motion and disability cannot be managed with a non-operative program, a total shoulder replacement can provide remarkable relief from pain and allow a much improved level of activity.

    Other arthritis which may damage the shoulder includes rheumatoid arthritis, other inflammatory arthritis and arthritis which develops after fractures or trauma to the shoulder joint.

  • 3) How long does it take to recover from the operation ? Open or Close

    The operation is usually done under a general anaesthetic. The patient stays in hospital for between 2 to 3 days. The shoulder is protected in an arm sling for a period of 6 weeks. A staged rehabilitation program is recommended by Dr. Ho and this goes on for about 3 months. Early, but supervised, motion of the shoulder is encouraged.

  • 4) The “Reverse” Total ShoulderReplacement Open or Close

    In a healthy shoulder, the rotator cuff muscles help position and power the arm during range of motion. A conventional replacement device also uses the rotator cuff muscles to function properly. In a patient who needs a shoulder replacement but who also suffers from a large rotator cuff tear, these muscles no longer function. In this situation, a conventional total shoulder replacement will also suffer and have poor results. The Deltoid muscle is the first layer of muscle covering the shoulder. This can be easily seen and felt on the shoulder. It is a powerful shoulder muscle but can only work properly when the rotator cuff muscles are acting. Fig 2: Reverse Shoulder Replacement A conventional shoulder replacement device mimics the normal anatomy of the shoulder: a plastic "cup" is fitted into the shoulder socket (glenoid) and a metal "ball" is attached to the top of the upper arm bone (humerus). In a reverse total shoulder replacement, the socket and metal ball are switched. The metal ball is fixed to the socket and the plastic cup is fixed to the upper end of the humerus. This arrangement changes the mechanics of the shoulder joint by moving the pivoting point toward the centre of the body. By doing this, the Deltoid can act without the rotator cuff muscles. A reverse total shoulder replacement works better for people with cuff tear arthropathy because it relies on different muscles to move the arm. The reverse total shoulder replacement relies on the deltoid muscle, instead of the rotator cuff, to power and position the arm.

    The operation is usually performed for patients who suffer from:

    • The effects of severe arthritis and rotator cuff tearing (cuff tear arthropathy)
    • Completely torn rotator cuffs with severe arm weakness
    • A previous failed shoulder replacement


Rotator Cuff Tears

  • 1) What is the Rotator Cuff ? Open or Close

    The rotator cuff muscles are the deep muscles in the shoulder. There are three groups of them. One helps to elevate the shoulder in actions such as reaching up to a high shelf. This is situated at the top of the shoulder and is called the supraspinatus. This is the most common muscle that is injured or torn. There is also one situated at the front of the shoulder, the subscapularis, which helps to turn the arm inwards such as when tucking in a shirt. There is a third group at the back of the shoulder, the infraspinatus and teres minor. These help in actions such as reaching out for a seatbelt. These muscles converge to tendons and attach at the bone at the top of the arm, rather like a cuff.

    Rotator Cuff Normal

  • 2) What sort of problems could be expected in a Rotator Cuff tear ? Open or Close

    The typical symptoms arising from a rotator cuff tear are pain and weakness. There is some pain at night when the patient tries to lie on that shoulder. More often, there is pain when trying to elevate the arm above shoulder level. They may find weakness when trying to lift and to put things onto a high shelf.

    Fig 2: Rotator Cuff Tear

    The tears occur at the tendon part of the muscle close to the bone. The remainder of the tendon pulls away from the bone and creates a defect at the rotator cuff. If you rub along the top of the shoulder you will find a shelf of bone. The rotator cuff muscle normally glides under this shelf of bone when the arm elevates. The defect in the rotator cuff frequently gets caught below this bony shelf and causes a problem of impingement. The result is pain during elevation of the arm.

    Once the rotator cuff tendon becomes detached, it will not be able to return to its original position at the bone and therefore spontaneous healing is unlikely. Some improvement may result over a period of time when the acute inflammation and swelling from the tear decreases.

    If the tearing process continues, the tears can develop into a larger tear and the muscle may become thinner. A large tear is technically more difficult to repair than a small tear.

  • 3) Treatment options for Rotator Cuff tears Open or Close

    The treatment options for rotator cuff tears are often individualised according to the level of symptoms and the physical requirement of the use of the shoulder. The aim is to decrease pain and to restore function of the shoulder.

    The non-operative treatment for rotator cuff tears includes physiotherapy and steroid injections. Physiotherapy mainly works by training and encouraging the healthy rotator cuff muscles and also the muscles around the shoulder blade in order to compensate for the torn tendons. The steroid injection works by decreasing the acute inflammatory swelling at the tear and also decreasing the inflammation in the pockets of fluid around the shoulder joint. This may help the pain.

    The operative option usually consists of bringing the torn edge of the rotator cuff back to the bony site at the top of the arm where it was once attached. There the cuff is stitched and the sutures are then drawn into the bone by either making bone tunnels or specially designed “suture anchors”. The sutures hold the cuff to the bone until the cuff tendon eventually grows onto the bone and take root. The operation is aimed to improve the pain and the strength of the shoulder. The operation also helps to address other associated problems with the rotator cuff tear, if needed.

  • 4) Is surgery necessary to treat Rotator Cuff tears ? Open or Close

    The American Academy of Orthopaedic Surgeons provides a good summary, as follows:

    Your doctor may recommend surgery for a torn rotator cuff if your pain does not improve with nonsurgical methods. Continued pain is the main indication for surgery. If you are very active and use your arms for overhead work or sports, your doctor may also suggest surgery.

    Fig 3: Rotator Cuff Repair

    Other signs that surgery may be a good option for you include:

    • Your symptoms have lasted 6 to 12 months
    • You have a large tear
    • You have significant weakness and loss of function in your shoulder
    • Your tear was caused by a recent, acute injury"


  • 5) Minimally invasive surgery for Rotator Cuff repair Open or Close

    Minimally invasive cuff repair involves either arthroscopic or arthroscopically assisted techniques. This is also known as a “key-hole” technique. An arthroscope is an instrument the size of a pencil. It has a live video camera at the end with a shining light. The images are shown on a TV monitor so that the inside of the shoulder can be viewed. A few small incisions just large enough to allow passage of the arthroscope and the instruments to do the repair are used. These incisions are considerably smaller than those used in the traditional open techniques. The hospital stay is generally shorter and most patients go home within 24 hours after the surgery.

Total Hip Replacement

  • What is a total hip replacement? Open or Close

    Who needs a total hip replacement?

    Patients who suffer from pain and stiffness in the hip joint. This is usually associated with a worn out hip joint from arthritis (fig 1,2, 3).

    The most common form of arthritis is osteoarthritis; others include rheumatoid arthritis, avascular necrosis of the hip and arthritis due to a wrongly developed hip (hip dysplasia). Patients with milder symptoms or early disease can try non-operative measures first such as medications, various types of physical therapy, curtailment of over vigorous physical activities and weight watching.

    Components of a total hip replacement

    Basically there are two parts to a total hip replacement. Firstly, the worn surface of the socket is “scraped” by a motorized surgical instrument during the operation. An artificial socket is then fixed to this “freshened” bone, and forming the new socket. Secondly, the worn head of the femur is removed and replaced by a new ball. Usually the new head is joined to a metal stem that goes inside the central canal of the upper femur (thigh bone) so that it can gain support from and anchorage to the bone. (fig 4)

    More than 25,000 primary total hip replacements have been put in over the last year in Australia. This is one of the most commonly performed orthopaedic operations and enjoys a high success rate (medical literature reported that some 86% of patients rated their total hip replacement as successful).....

    Fig 3 X-ray of an osteoarthitic hip
    Fig 3 X-ray of an osteoarthitic hip
    Fig 4 X-ray showing a total hip replacement
    Fig 4 X-ray showing a total hip replacement


  • What to expect from a total hip replacement? Open or Close

    Having mixed feelings?

    There is no doubt that a Hip Replacement is a major event in one’s life. It is quite natural to experience mixed feelings of hope and fear. As doctors we help the patient to understand the operation and alleviate unnecessary fear. At the same time, it is also important to make sure the patient’s expectations are realistic.

    The Hospital Stay.

    Generally speaking, the operation takes about two hours. With my hip replacement patients on the Sunshine Coast, the usual stay is 3 to 5 days in the acute ward after their operation. Following this they have the option of going into a rehabilitation hospital, such as Eden at Cooroy or the rehab unit of the Sunshine Coast Hospital at Buderim. The average duration in rehab is 7 to 10days.

    Duration of Recovery.

    By the time the patients go home, they are usually very independently mobile. Walking aids are usually not needed by the fourth week. It often takes 3 months for the patient to feel completely better and be ready to return to most, if not all, normal daily activities.

    What activities can one do after a Hip Replacement?

    Information regarding activities one can undertake after one’s hip replacement can be obtained from a diversity of sources. Some practices that freely advertise their services tend to play up the expectations and play down on the potential risks. I believe it is fair to look at recommendation as put forward by the American Academy of Orthopaedic Surgeons at http://orthoinfo.aaos.org/topic.cfm?topic=A00356

    How long will the hip last for?

    The Australian Joint Registry statistics show that at the 10 year point, 6.2% of hip replacements have been revised, or if you like, have failed. Overall a 10 to 15 year longevity is a realistic expectation.

  • Types of hip replacement by fixation methods Open or Close

    There are in general two ways that the prosthesis are fixed firmly to the bones. Bone cement is used in one type (cemented). The other type uses a press-fit mechanism (non-cemented).....

    Cemented total hip replacement.

    Here bone cement is applied like “glue” in between the prosthesis and the bone cavity. Bone cement is made of polymethyl methacrylate or PMMA. The stem is usually made of metal and the cup is wholly plastic. E.g. Charnley, Exeter (fig 5)

    Fig 5---A drawing showing a cemented femoral prosthesis Non-cemented total hip replacement

    Here the “immediate” fixation is by press-fit. The femoral or acetabular cavity is prepared slightly undersize to the real prosthesis. Therefore when the prosthesis is driven into place, it achieves a firm fit. Most of the prosthesis have a special coating on the surface. These coatings are designed to stimulate new bone to grow from our bone onto the surface of the stem. This will then provide “long term” fixation to the prosthesis. These coatings include: porous coating with sintered beads; porous with Hydroxyapatite (fig 6) and Titanium structures (fig 7).

    Hybrid total hip replacement.

    In this category, one of the two components is cemented and the other part non-cemented. E.g. non-cemented cup with a cemented stem or non-cemented stem with a cemented cup.

    Which one is better, cement or non-cemented?

    Both have their advantages and disadvantages. It comes down to surgeons’ preferences and beliefs. At present, in Australia, about 60% surgeons used non-cemented prosthesis. About 40% use either fully cemented or hybrid (one part cemented) prosthesis.



  • Types of total hip replacement by material Open or Close

    • Different materials have been used successfully in total hip replacement.
    • Certain materials are used to build the body of the prosthesis. They need to be strong to prevent breakage and are metal. These include Stainless Steel, Cobalt and chrome alloy and Titanium.
    • Certain materials are selected to make up the part of the prosthesis to provide the movement surface. These material need to have a very smooth surface and some strength. These include surgical plastic or Ultra-high-molecular-weight-polyethylene (UHMWPE) (fig 8), Ceramics and Cobalt-chrome alloy (metal) (fig 9).
    • The stem and socket each usually consist of two parts. They are put together by the surgeon during the operation. The stem usually consists of a head and a body. The socket consists of a liner in a metal shell (fig 10). For example, a ceramic head on a metal stem moves against a plastic socket, which in turn sits on a metal backing which press-fits in the acetabulum. There are many combinations of movement (bearing) surfaces, please refer to the next section.

    An acetabulum cup
    Fig 8
    Fig 10. Plastic liner within a metal acetabulum shell
    Fig 10

  • Types of Hip replacement by movement (bearing) surfaces. Open or Close

    Metal head on plastic socket (fig 11)

    This has a long history of use and is well tested. The plastic will eventually wear away limiting the ultimate longevity of the hip replacement. The newly developed highly-cross-linked plastic shows much improvement on the wear factor and has been adopted and produced by many manufacturers.

    Ceramic head on plastic socket

    Ceramic heads have smoother surfaces and better wear characteristics than metal head. Some of the early versions suffered from breakage as they were more “brittle” than metal. The newer versions show some early promising results.

    Ceramic head on ceramic socket (fig 12)

    Ceramic moves nearly frictionlessly on another ceramic surface and ceramic on ceramic showed the least wear (i.e. the best wear characteristics) amongst all types of movement surfaces. Unfortunately ceramic on ceramic tolerates technical imperfections in surgery poorly and could develop problems if these occur. Squeaking noise is also sometimes a concern.

    Metal head on metal socket (fig 13)

    This wears better than plastic although not as good as ceramics. Metal is stronger than ceramics and breakage is not a concern. Metal on metal was once a popular choice but recently declined in its use due to reports of some early failure, product recalls from some manufacturers and potential concerns of raised metal ions in the blood stream.

    Hip Resurfacing hip replacement (fig 14 a & b)

    This is also a metal on metal bearing surface. The socket is the same but a stem is not used. A metal “cap” is applied to a “trimmed” femoral head bone instead. This conserves bone on the femoral side and allows an easier revision operation in the future.

    Fig 14a A photo and X-rays of a Hip Resurfacing total hip replacement.
    Fig 14a A photo and X-rays of a Hip Resurfacing total hip replacement.

Knee Replacement

  • Knee Replacement Open or Close

    Knee Replacement

    Who needs a Knee Replacement?

    The most common reason for this operation is severe Osteoarthritis of the knee Joint. Other reasons includes different types of arthritis such as rheumatoid arthritis. The Knee is a Joint, right? But, what is a Joint?

    What is a Joint?

    A joint is where two or more bones meet. The joint allows the bones to move freely within its limits. The knee is the largest joint in the body. It needs to be strong enough to take our weight and must lock into position so we can stand upright. However it also has to act as a hinge so we can walk, climb and must be able to withstand stress, twists and turns, such as when we run or play sports. So, what has gone wrong in the knee joint, is it something to do with the cartilage? [h4]What is a cartilage?[/h] The knee joint is where the thigh bone (femur) and shin bone (tibia) meet. The end of each bone is covered with cartilage which has a smooth, slippery surface which allows the ends of the bones to move against each other almost without friction. (The knees have two additional rings of cartilage between the bones. These are called menisci – they act a bit like shock absorbers to spread the load more evenly across the joint.)

    What is Osteoarthritis?

    Osteoarthritis is a disease that affects the body’s joints. The condition is sometimes called arthrosis, osteoarthrosis or degenerative joint disease. This is largely regarded as a wear and tear situation often promoted by previous injuries. When a joint develops osteoarthritis, the surfaces of the joint are damaged so the joint doesn’t move as smoothly as it should. The cartilage covering the ends of the bones gradually roughens and becomes thin. This causes pain, swelling and stiffness resulting in restriction to the person’s mobility and various physical activities.

    How much bone is removed in a knee replacement?

    The purpose is to remove the damaged coating cartilage at the end of the shin and thigh bones in the knee joint. Usually a thin layer of bone about 9 to 10mm is also removed with the damaged cartilage. The soft tissue that envelops the knee including the important ligaments and tendons are preserved.

    What materials are used in a knee replacement?

    Many different types of designs and materials are currently used in total knee replacement surgery, nearly all of which consist of at least two components: the femoral component (made of a highly polished strong metal) and the tibial component (made of a durable plastic often held in a metal tray. If the patella also requires replacement, the damaged coating cartilage will be removed with about 9mm of bone and replaced with a new plastic cap. The main body of the patella is preserved. The femoral or thigh bone component sits on the top and is commonly made of cobalt-chromium-molybdenum alloys. It is shaped like a large curved cap. The tibial or shin bone component sits on the bottom where a surgical grade plastic is supported on a metal tray commonly made of Titanium alloy. The plastic is shaped in the opposite concave curvature to match the femoral metal curved cap above and this becomes the new smooth moving surfaces of the knee instead of the damaged cartilage. These components are fixed to the bone commonly with the use of bone cements.

  • Recent Developments Open or Close

    While the conventional techniques of a Knee Replacement work well, there has been some recent developments in an attempt to refine the technique to make it more accurate. Some examples are given below.

    Gender Specific Knee Replacement

    This is based on the knowledge that the dimensions of the knee bones in females are different from males to some extent. Prosthesis which are made to match female bones more closely are now available. The theoretical advantage is that by better replicating the normal anatomy, the joint replacement implants may allow for better function, as well as improved durability.

    Computer Navigated Knee Replacement

    An infrared system is used during the operation to detect the real time positions of the bony structures of the knee. Like a radar, it scans and displays a 3D model of the patient's knee on a computer screen. The image of the knee allows the surgeon to see inside the joint and more exactly align the bone and implanted material in the knee. The theoretical advantage is that better alignment gives rise to better longevity of the knee replacement.

    Patient Specific Instrumentation (PSI)

    This newly available technology utilizes MRI technology and computerized planning tools to create customized cutting guides that are tailored to each patient’s unique anatomy. These customized guides are made in Europe based on the information obtained from the MRI scan of the patient’s knee before the operation. Once manufactured these customized guides are sent to the operative theatre for the surgeon to use. The theoretical advantage is that it increases the accuracy of the knee replacement and therefore better results.