Clinical Results

, Paul D. Siney¹ and Patricia A. Fleming¹

(1)

The John Charnley Research Institute Wrightington Hospital, Wigan, Lancashire, UK

The clinical results of this operation are so good that one often feels they are too good to be true.

The driving force behind the development of total hip arthroplasty was Charnley’s desire to help patients disabled by painful arthritic hips. The surgical procedures available: intertrochanteric osteotomy, arthrodesis, or excision – pseudarthrosis – did not offer predictably significant clinical benefit; and if they did it was only limited and in a carefully selected minority.

It is interesting that pain, hip pain, the main indication for surgery, has received so little detailed attention. True enough, every assessment scoring system includes pain – even at times using visual analogue scale – but none define hip pain.

At some stage on the “patient pathway” and almost certainly very early on – and maybe even before the patient is seen – an assumption is made that the problem is “a painful hip”. Very often the radiograph is seen before the patient becomes the focus of attention.

Deep seated structures, when affected by a disease process, do not offer localising symptoms – certainly not initially. It is generally assumed that pain from an arthritic joint arises in the worn arthritic joint surfaces. After all, an intra-articular injection of local anaesthetic offers immediate relief of pain. What about the capsule? At some stage it was considered the source of pain and the cause of fixed deformities. Excision of the capsule has never been the part of the Charnley hip replacement, although some limited exposures did advocate the excision of the capsule.

The immediate relief of pain remains the driving force behind the surgery of total hip arthroplasty. The relief of pain is considered to be the success of the treatment offered. And yet, pain can only be experienced by the sufferer. Painful episodes cannot be quantified in terms that can be understood, compared with that of other sufferers or recorded in the memory for any future reference – a fortunate state for the human race.

Any attempt to assess, record, recall or compare the results of a treatment must understand and accept the limitations. In short – pain is personal and so is the relief from it.

In clinical practice where brevity, simplicity and comparability is essential; the d’Aubigne and Postel method of assessment [1] as modified by Charnley [2] continues to be most practical. Pain relief after successful THA has practical implications for follow-up. A natural symptomatic joint, replaced with a neuropathic spacer cannot become symptomatic unless the failure involves the living structures – a late and often very late state of affairs.

Activity level achieved as a result of a successful THA is not a characteristic of a particular design, material or even a method of component fixation – certainly not in the short term – it is a reflection of patient selection for the operation. Activity level advertises success, attracts would be candidates some of whom may have unreasonable expectations.

Single case success is attractive both clinically and commercially – a most unfortunate combination.

It is interesting how the range of hip movement has received little attention. Freedom from pain need not be accompanied by full range of hip movements except in very exceptional cases and situations.

In preoperative assessment, patient selection and identification of the source and severity of the problem is most essential. At follow-up comparison of serial radiographs is mandatory.

Clinical Assessment

Successful clinical results uncovered the demand and extended the indications for the operation. Pressure of numbers and the increasing costs focused the attention on the financial implications. Initially the operation was used as a “unit of currency” against which the cost of other procedures was assessed. More recently the cost-benefit ratio, for individual patients, expressed as “quality of life”, is becoming the standard. This is not unexpected. Pain – hip pain – is not immediately obvious to an observer. Furthermore, severity of pain does not usually leave a permanent imprint on our memory – fortunately.

Restriction of movement or activity may be more obvious but only to those close by. Activity level, achieved as the result of freedom from pain, becomes clear for all to see without the need for explanation or comment.

Thus hip pain, the indication for the operation is quickly forgotten, while activity level advertises individual clinical success and becomes the target for would be patients to aim for.

The indications for the operation and the patients expectations have moved away from pain relief to expected activity level.

In clinical practice viewing of radiographs often comes before clinical assessment. In this context the term: “end-stage arthritis” is becoming common; a most unfortunate development. It is not only unscientific but full of emotional overtones. History and examination must come first. A radiograph shows me what the hip looks like but the patient tells me what it feels like!

History

Patients presenting for consideration of hip replacement surgery are often “self-selected” and maybe even “self referred.” They may already have a record of previous consultations. More often than not they may have preconceived ideas as to what benefits are to be had from a successful hip replacement. It has been observed over the past 40 years or so that the type of patient has gradually changed. In the 1970s patients often presented late in the disease process. Pain was often severe, disability great, deformities marked, dependence on sticks or crutches common. Then followed a period when patients presented with fears of “being confined to a wheelchair”. More recently high expectations are the order of the day. Why this changing pattern? Confidence and familiarity and unreasonable claims of success – often based on the very early “single case success stories” may be some of the reasons.

Detailed history is essential and must follow a clearly set pattern no matter that the problem and the decision as to treatment are immediately obvious. By the time the patient enters the consulting room every opportunity must be taken to establish a relationship which may be for a lifetime – either of each other or of the arthroplasty.

Time of onset and duration of symptoms, pain patterns, its effect on daily activities, patient’s understanding of the problem, but above all knowledge of the disease process, the likely progress and finally the ins and outs of surgery. After physical examination, then and only then, should the radiograph be viewed. It is not the purpose of this work to spell basic details of history taking and examination.

Young patient, long history, would suggest congenital problems. Female patient with restriction of all movements apart for flexion – probably protrusio. Muscular male with a history of sporting activity – could be slipped upper femoral epiphysis. Grumbling pain with full movements of the hip, be on the lookout for avascular necrosis. Sudden “collapse” rare – beware of something unusual or even sinister here, special investigations may be indicated.

Be on the lookout for leg length discrepancy. Disease process – other than protrusio or early AVN – should result in limb shortening. Apparent limb lengthening, of which the patient is invariably unaware, indicates early arthritis with a well preserved proximal lever, femoral head contained within the acetabulum.

Beware of fixed pelvic obliquity due to long standing spinal problems. All problems may not be solved by THA and leg lengthening after surgery will be bitterly complained of. First consultation need not lead to surgery.

A word of warning about a congenital dislocation of the hip with secondary degenerative changes, adduction deformity and symptoms severe enough to warrant surgery. The contralateral hip dysplasia may not be obvious because of the pelvic obliquity. Successful hip replacement “uncovers” the dysplastic hip, arthritic changes – now symptomatic – may follow rather quickly. What must not be forgotten with limb length discrepancy is that the knee on the longer side functions in flexion, degenerative changes of the knee may follow. The knee on the side of the adducted hip functions in valgus. Levelling of the pelvis after THA exaggerates the valgus of the knee which makes walking difficult.

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