Gary Culliton reports on the visit of a leading expert in orthopaedic surgery who came to Ireland recently to educate doctors on pioneering minimally-invasive hip surgery.
A novel hip replacement technique was demonstrated at the Midland Regional Hospital, Tullamore, during three operations on February 29 and four procedures on March 1.
Pioneering orthopaedic surgeon Dr Erik De Witte from the General City Hospital (ASZ) in Aalst, Belgium, has specialised in procedures appropriate to hips. He believes the Anterior Supine Intermuscular (ASI) approach for total hip arthroplasty is a safe, reproducible technique with good short-term results and a complication rate comparable to or even lower than that of other approaches.
Mr David Cogley and Mr Eoin Sheehan, orthopaedic surgeons at Tullamore, performed the surgery, while Dr De Witte — an expert in the minimally-invasive direct anterior approach for hip replacements — participated and also gave lectures to a number of consultants from around the country who were in attendance. Since 2004, Dr De Witte — who retired on December 31 — has performed the anterior supine intramuscular (ASI) approach to hip replacement 3,500 times.
A minimally-invasive surgery (MIS) approach to the front of the hip aims to reduce the trauma of soft tissue entry, explained orthopaedic surgeon Mr Fergal McGoldrick, who along with Mr Cogley was scheduled to speak on MIS at a Hermitage Clinic GP educational meeting in Mullingar on March 14.
In future, surgeries are likely to involve much smaller incisions, explained Mr McGoldrick, with a quicker recovery time the claimed advantage of the surgery from the patient’s point of view. The surgery is a technically demanding procedure with a sharp learning curve, Mr McGoldrick added, and there are risks of neurovascular injury in the area. However, if done correctly, as devised, the operation is safe and there is a definite short-term advantage in that patients are out of hospital quicker. There is also lower morbidity and less soft tissue trauma, he said.
At six months, however, outcomes for smaller-incision surgery were no better than for larger incision operations, Hip Registry data published last September show, and at 10 years, survival data are not quite as good for MIS as for traditional operations, added Mr McGoldrick.
Dr De Witte assisted at the first three recent procedures at the Hermitage.
As with some other techniques, the aim is to get people out of bed and walking the same day.
The main advantage of the technique is that it can be done through a 10cm incision. ASI uses an incision at the front of the hip instead of the side or back. This incision placement allows surgeons to directly approach the hip by going between, rather than through, the muscles that surround it. The goal is to thus minimise muscle and tendon disruption, making surgery less traumatic for patients, allowing for shorter hospital stays and quicker recoveries.
Importantly, muscle is not cut and this tends to be less painful, explained Mr Cogley, who is based partly at Tullamore and partly at the Hermitage Clinic in Lucan. He studied the technique two years ago, at a number of courses in Vienna, and has been using it for the past 18 months.
“Most of the pain receptors seem to be in the muscle and tendons around the hip joint. As they are not cut, the procedure tends to be a lot more comfortable and there is less interference with the patient’s physiology, making the recovery a lot quicker.”
The average length of hospital stay for a hip replacement is between six and seven days. The ASI patients have been returning home two or three days after surgery, it is claimed. “They come off crutches and can drive three or four weeks later,” Mr Cogley said. When surgeons are skilled in the technique, the hope is this will lead to shorter inpatient stays and reduced costs for hospitals, added Mr Cogley.
Sir John Charnley pioneered low-friction arthroplasty using a transtrochanteric approach. The posterior approach and the direct lateral approach, or Hardinge approach, followed. Subsequent to this, that approach was still employed but the incisions were shrunk, leading to short-incision surgery using the posterior or direct lateral approach. The different incisions used in a hip replacement surgery are all defined by their relation to the musculature of the hip. The approaches are posterior (Moore or southern), lateral (Hardinge or Liverpool), antero-lateral (Watson-Jones), anterior (Smith-Petersen) and greater trochanter osteotomy.
The traditional hip replacement approach was a trochanteric osteotomy. That had a high complication rate with non-union of the trochanter a possibility. The process involved wiring, and the danger was that there could be wire breakage and wire irritation. There were also dislocations with the monoblock hip.
Ten years ago, incisions were typically almost a foot long; the trochanter was removed to get at the hip joint. When the trochanter was removed, it often took three months for the patient to recover from the operation and to be able to discard their crutches. While modifications of standard techniques such as the posterior or lateral approaches have evolved using shorter incisions, studies have suggested that there is no difference in patient recovery using a posterolateral or direct lateral approach, whether the incision is large or small.
There has been an evolution in the technique. While current levels of ‘invasiveness’ are similar, incisions have been shrinking. An 8cm to 10cm incision now suffices for most patients. Yet there is no difference in recovery time with the small incision approach, said Mr Cogley.
The posterior approach was popular for metal-on-metal hip replacements. This method was popular in England in particular, though a small ball introduced through the posterior approach has a dislocation rate of up to 20 per cent, said Mr McGoldrick. Thus in the 1990s, there was a move towards the anterior approach.
The ASI approach to the hip joint is part of a very old technique, the Smith-Peterson approach, originally designed by Karl Heuter, a German surgeon in the early 1870s and employed since 1974 using a fracture or traction table by Letournel and Judet in Paris for hip replacements. The procedure has evolved since the early 1990s. It is extensile; if there are problems, the incision can be safely extended.
Kim Berger in America has described a two-incision technique. He made an incision in the groin to cut the femoral neck and remove the femoral head. He then put in the acetabular component of the hip replacement. Next, a small incision was made over the top of the trochanter and the femur was reamed. A femoral component was inserted and the sections connected. The two-incision technique was technically difficult, and much work had to be done under image control. A particular type of uncemented hip replacement was used to fill the marrow cavity of the femur.
Michael Nogler subsequently, in the early 2000s, evolved this technique; he was able to elevate the femur into the wound, making this accessible and therefore the whole procedure could be done through one incision.
If working on the principle that less soft tissue morbidity is achieved with an MIS incision, the long-term clinical cost/benefit advantages for patients over a lifetime — measured by Quality-Adjusted Life-Year (QALY) score — have not been conclusively established, added Mr McGoldrick. There may be a saving to the system of between three and five inpatient bed days with a novel approach. In terms of a Hip Society score at six months — when the quality of life and productivity of patients in society are evaluated — an advantage has not been proven.
The ASI approach effectively uses the same interval between the muscles as Berger to remove the head of the femur and put in the socket. This is a popular approach in Europe and has been used in France for a long period of time, as well as in central Europe and Belgium. In the US, between 10 and 15 per cent of all the hip replacements are now carried out using direct anterior approach. In Japan, 60 per cent of all hip replacements are done through the direct anterior approach. “The main driver for this technique is patient satisfaction,” added Mr Cogley. He said there had been a huge improvement in short-term patient function since the days when the trochanter was removed. The period on crutches was reduced from three months down to four weeks. In terms of function, the advantages do appear to be short term as there does not appear to be a major difference between techniques one and two years after the procedure and any differences would appear to be quite subtle, said Mr Cogley.
The procedure should be used in conjunction with a rapid recovery or joint school programme, he added. This involves standardisation of pre-operative patient education and bringing patients into hospital to interact with surgeons, physiotherapists, nurses and anaesthetists prior to the surgery. In this way, patients are aware of what the surgery entails and what would be expected while in hospital and the duration of hospital stay.
Peri-operative protocols — including maximisation of pain relief, early return to function and early discharge from hospital — seem to improve both recovery from the operation and patient satisfaction from the whole procedure, added Mr Cogley.