Boutonniere and Swan-Neck Deformities
(PIP joint deformities)
What is the finger PIP joint and what deformities occur?
The PIP joints are the middle joints of the fingers. They are shaped as double domes side by side on the hand side of the joint and two side by side matching shallow curves on the finger side. This allows mobility in bending and straightening but stability in sideways and twisting movements. The PIP joints are therefore very stable but this makes them more prone to stiffness and other problems.
PIP joint imbalance: Two main types of deformity are described: Boutonniere deformity; and Swan-neck deformity.
Boutonniere deformity: This describes a condition where the PIP joint will not straightened under its own power (actively) but can be straightened by the other hand (passively). In addition the end joint of the finger (DIP joint) over straightens and will not bend (flex) fully. Patients typically present in young adulthood following an injury or later (40yo and onwards) due to some joint arthritis. With enough MP joint (first joint of the finger) excess straightening the patient can often place their hand flat on a surface. In time the correctible deformity may become stiff and more disabling and lead to further joint damage.
Swan-neck deformity: This describes a condition where the PIP joint over straightens due to laxity of the restraining ligament on the palmar side of the joint. This is present in many normal people especially in young ladies and in Asians due to greaterligament laxity. Normally it is not a problem, but if it is sufficiently marked the patient may be unable to initiate bending of the PIP joint with their own finger muscle and need help from the other hand which is a nuisance. The finger can gradually become stiffer and fixed in an over straightened position which is very disabling. Swan-neck deformity is not usually painful.
Why does it occur?
Boutonniere deformity: There is a complex arrangement of tendons around the PIP joint. In the boutonniere deformity the main tendon straightening the joint is damaged/stretched so full active straightening is not possible. In an effort to straighten the joint other tendons overact leading to excessive forces on the end joint stretching it into over extension.
Swan-neck deformity: Normally the ligament on the palmar side of the joint called the volar plate prevents over straightening of the joint. When this is damaged the finger naturally sits in an over straightened position. This is seen most often following injury or childhood, adolescence or young adulthood that is overlooked. This is not a problem if mild but if marked prevents initiation of active bending i.e. starting bending of the finger on its own and even fixed over straightening which is functionally very disabling.
What happens if nothing is done?
(This is referred to as the natural history i.e. what happens if Nature runs its own course.)
Boutonniere deformity: Often a stable position is achieved which may remain reasonably static for a long time although in most cases the deformity gradually increases becoming more of a nuisance.
Swan-neck deformity: Most of the time the deformity does not progress. The more marked the deformity the greater the likelihood of progression.
Making the diagnosis
The Hand specialist who sees the patient will ask questions about their symptoms, when they started, how they progressed, what treatment (if any) they have had and other questions relevant to the problems. They will then examine the patient looking at the wrists and hands. Stressing i.e. pushing on the affected joint is not usually painful but may be but this should not be too painful.
What test(s) might be performed?
Tests (also known medically as Investigations) include X-rays, scans, blood tests and particularly in the hand electrical tests (known as EMGs or Neurophysiology). These may be used to help make or confirm a diagnosis after a patient has described their symptoms and been examined.
The diagnosis is usually obvious after listening to and examining a patient. Typically an X-ray is requested on the same day to delineate the extent of joint damage (if any), although the X-ray findings do not correlate well with the symptoms with some patients having few X-ray changes but marked symptoms and vice versa.
Treatment:
What are the non-operative treatments?
Boutonniere deformity: If treated early particularly when mobile then it usually settles very well with splintage: full time for the PIP joint for 6 weeks in extension ensuring DIP flexion and then gentle mobilisation. If the joint is painful a steroid injection is usually recommended to settle the pain and inflammation. An injection is given of a long-acting steroid, such as Depomedrone or Triamcinolone, with some local anaesthetic into the joint at the bottom of the thumb. The body naturally produces steroids to help dampen down inflammation. This appears to be one of the actions at this site. Success cannot be guaranteed but in 80-90% of patients there is significant benefit. Only occasionally does the injection need to be repeated.
Swan-neck deformity: Most patients do not need treatment. If they do then splintage may help but surgery is usually necessary.
What does the operation involve?
Boutonniere deformity: The operations are one or both of: a joint release and a reconstruction of the extensor mechanism.
Both operations are typically typically performed under local anaesthetic. The joint release is performed through 2 incision one either side of the joint. This is required for cases that have not stretched out with splintage. After correction of the joint (which is usually but not always complete) the joint may be held straightened with a wire across the joint for a few weeks (this is removed in the outpatients clinic). The skin is closed with absorbable sutures. Then either at the same time although often later, the extensor mechanism can be corrected but it may settle sufficiently with splintage once the joint contracture has been released. At operation a longitundinal (in the line of the finger) cut is made along the back of the PIP joint. The tendons are mobilised and reconstructed. The joint may be held straightened with a wire across the joint for a few weeks (this is removed in the outpatients clinic).
The total time in hospital is usually 4-6 hours.
Swan-neck deformity: The operation is one or both of: volar tenodesis and dorsal release.
The volar tenodesis is a soft tissue tie on the palmar side of the joint preventing over straightening. If the joint is fully mobile this should suffice. If the joint is stiff (lacking bending) then a dorsal release i.e. a release of the tight tissues on the back of the joint.
Both operations can be performed under local anaesthetic. A volar tenodesis requires a tourniquet on the arm. A band, like a blood pressure cuff, is placed around the top of the arm. It is inflated (tightened) during the operation to reduce bleeding, which makes the operation easier and safer. It can be a little uncomfortable, but is almost always well tolerated for the 20 mins or so that it is inflated (this happens just before the surgeons starts the operation). Before that the arm is painted with an antiseptic with a pink dye in it. This is used to help minimise the risk of infection. If a dorsal release is performed this is done first with a base of finger tourniquet which the patient does not feel.
A volar tenodesis involves opening the front of the finger via a zig-zag incision and taking part of one of the finger bending tendons and using this as a tie to prevent over straightening. (Typically it is a little over tightened leading to a mild loss of flexion as this is preferable to a recurrent deformity). A small wire may be passed across the joint for a few weeks. It is removed in the outpatient’s clinic. The skin is stitched with absorbable stitches.
A dorsal release is performed via a curved incision over the back of the finger and the tight tissues released to allow full bending of the finger. The skin is stitched in part with absorbable stitches. Some of the skin may be left open to optimise healing. The open section heals on its own.
What happens in the next few weeks?
The care of the hand in the post-operative period is very important in helping to ensure a good result. Initially the aims are comfort and elevation. These are met by keeping the hand up (elevated) especially in the first few days and by use of a long acting local anaesthetic (Bupivicaine). The local anaesthetic lasts at least 12 hours and sometimes 48 hours. Patients should start taking painkillers before the pain starts i.e. on return home and for at least 24 hours from there. This way most of our patients report little or any pain.
The patient is reviewed in clinic after about 1 week following the operation. Typically dissolvable stitches are used so they should not require to be removed. A splint will be provided by the physiotherapists. Careful follow up is required to ensure a successful result with good relief of pain and a good range of movement. The wire if used is removed in clinic at about 3 weeks form surgery. Therafter the hand can be used whilst still wearing the splint protecting against over straightening. Most of the movement gained following surgery occurs in the first 6 weeks and this time must be used productively to ensure a good result. The key is regular long gentle stretches both into straightening and into bending. Ideally these should be performed for 5 mins in each direction (feeling the stretch but without pain) once an hour. In practical terms most people mange 5-6 times a day. Elevation and icing the elbow also help reduce swelling and thus pain and improve movement.
Most patients can drive after a 4-5 weeks. Most patients return to work in 5-6 weeks, but this varies with occupation; heavy manual work usually takes about 3 months if ever. The wound should be massaged by the patient 3 times a day with a bland soft cream for 3 months once the wound is well healed (typically after 2 weeks). This reduces the scar sensitivity which can be a nuisance. If this is marked a Physio may be organised to help reduce the scar tenderness but this is rarely required. Patients should avoid pressing heavy use of the hand for a good 3 months from surgery.
What are the results of the operation?
Boutonniere correction: This is not a reliable operation and so is only used in the more severe cases. Most patients are happy with the result of surgery with improved movement and function, but full recovery never occurs.
Swan neck correction: At least 85% of patients in studies say they have a good or excellent result following this operation, with relief of the pain and a reasonable range of movement.
Are there any risks?
All interventions in medicine have risks. In general the larger the operation the greater the risks. For both boutonniere and swan neck correction the risks include:
- The scar may be tender, in about 20% of patients. This usually improves with scar massage, over 3 months.
- Aching,at the site may last for several months
- Grip strength can also take some months to return to normal.
- Stiffness may occur in particular in the fingers. This is usually short-term and only infrequently requires physiotherapy. But it is very important that it is resolved quickly to avoid permanent stiffness. This occurs rarely but can do associated with CRPS (see below)
- Numbness can occur around the scar but this rarely causes any functional problems.
- Wound infections occur in about 1% of cases. These usually quickly resolve with antibiotics.
- Recurrent deformity can occur following either procedure and occasionally requires a re-operation.
- Chronic Regional Pain Syndrome “CRPS”. This is a rare but serious complication, with no known cause or proven treatment. The nerves in the hand “over-react”, causing swelling, pain, discolouration and stiffness, which improve very slowly.
- Any operation can have unforeseen consequences and leave a patient worse than before surgery.