Introduction
Burman in 1931 scoped 3 ankles using a 4.Omm sheath without distraction, he found it too tight for satisfactory visualisation. Ankle arthroscopy really came of age in the 90's with the development of 2.5mm arthroscopes, noninvasive distraction techniques and irrigation systems.

Historical developments
Tagaki was the real father of the arthroscope. He developed a 2.7mm arthroscope. However Watanabe developed matters further producing a self-focusing 1.7mm arthroscope and arthroscoped 28 ankles, describing the standard portals and normal anatomy.

Andrews wrote one of many texts on the subject in the late 80's. Guhl developed a skeletal distracter for the ankle and wrote an excellent text.

Yates was the first to develop a non invasive distraction technique.

Advantages and Contra-indications
ADVANTAGES
Arthroscopy allows direct articular inspection + assessment of ligaments and synovial change. One can perform intraoperative stress testing.

The following diagnoses can be made. OCD - 23.5%, Impingement - 21.3%, Chrondromalacia - 7.9%, Instability - 7.2%, DJD - 7.2%, Acute Fracture - 6.5%, Arthrofibrosis - 4.8%, Loose Bodies, Osteophytes, Synovitis, Ossicles, Torn ATFL, Cryptogenic Pain, Cyst, Chondral Fracture, Peroneal Subluxation, Torn Peroneal Tendon.

The following procedures can be performed. Debride lateral gutter - 21.8%, Excise/Drill OCD - 19.4%, Chondroplasty - 13.3%, Excise fibrous bands - 6.8%, Loose bodies - 5.7%, Rx of fracture, Diagnostic, Synovectomy, Osteophytes, Ossicles, Arthrodesis, Stabilisation CONTRA-INDICATIONS - Relative - DJD, Oedema, Impaired vascularity.

Absolute - Soft tissue infection, Advanced DJD.

Instrumentation
Ankle arthroscopy developed from the principles of knee arthroscopy and hence initially the same instruments were applied. However as experience developed with smaller instruments, distraction, and fluid management systems, arthroscopy evolved.

Irrigation - Gravity, Gravity assist, Pumps.

Athroscopes - Hopkins 2.3mm, 2.7mm and 1.9mm diameters, 30 & 70 degree.

Distraction - Non invasive.

Instrumentation - Spinal needles, Probes, Dissectors - elevating OCD lesions, ossicles, Graspers - flat tipped or pitbull for small or large loose bodies (2.7-3.Omm), Basket forceps - straight, right and left, up and down angles (2.53.00mm), Knives, Curettes, Osteotomes, Power Instruments, Thigh/Ankle Holder, Aiming jigs.

Diagnostic Arthroscopic Examination of the Ankle
Ankle arthroscopy is a useful diagnostic modality to evaluate pathology and determine correct treatment. It should not be used as a substitute for careful history taking, examination and investigation. Its main advantages are that it allows direct inspection and probing of all intra-articular structures and their dynamic assessment. As such it is virtually 100% accurate in diagnosing intra-articular disorders.

The ankle is first distended with approximately 30cc of saline. Then the anteromedial portal is established just medial to tibialis anterior at the level of the joint line carefully avoiding the saphenous nerve. Then the anterolateral portal is established using transillumination, avoiding the superficial branch of the lateral popliteal nerve. A full diagnostic inspection of the anterior compartment is then carried out. Then the posterolateral portal is made localising the entry point with a spinal needle. Then a full inspection of the posterior compartment is made. Using these three portals a full 21 point systemic ankle examination can be carried out.

SOFT TISSUE LESIONS OF THE ANKLE
These are difficult to diagnose without arthroscopy despite careful assessment and investigation. They represent some 3050% of lesions found within the ankle joint and are diagnosed and treated by arthroscopy.

Patients with such lesions present with a combination of pain, swelling, tenderness, locking and giving way.

On examination one finds a combination of tenderness, wasting, swelling, restricted range and instability.

Investigations include XR, CT, MRI, Arthritis tests. These all may be negative.

CLASSIFICATION
Congenital - Plicae / bands - excise

Traumatic - sprains, fractures, prior surgery - excise generalised synovitis, excise localised bands, excise meniscoid lesions secondary to impingement.

Impingement lesions
Lateral ligament injuries are very common, with 1 ankle sprain per 10,000 occurring per day. Some 1-50% have some chronic pain.

Anterolateral impingementis the commonest soft tissue impingement lesion and cause of pain after ankle inversion injury - Wolin coined the term "the meniscoid lesions" for the arthroscopic appearance of the lateral gutter in these patients.

Arthroscopic treatment is very successful in alleviating chronic pain in 84% both subjectively and objectively.

During dorsiflexion of the ankle the malleoli are separated and the syndesmosis is stressed, syndesmotic injuries are undoubtedly underestimated. Syndesmotic injuries are best diagnosed by a localised tenderness and a positive squeeze test pressing the tibia and fibula together proximal to the syndesmosis half way up the calf.Syndesmotic impingementis also associated with a separate distal fascicle to the anterior talo-fibula ligament. The incidence of syndesmotic injury is 3% of all ankle sprains.

Posterior impingementcan occur and was first described by Hamilton with posterior "meniscus" displacing inferiorly. Also a labrum on the posterior lip of the tibia can hypertrophy when injured.

Inflammatory Lesions
Rheumatoid arthritis, X-tal synovitis, PVNS and Synovial Chondromatosis can all affect the ankle. Rheumatoid arthritis has been reported to have an arthroscopic cure. A 95% synovectomy is possible, and early synovectomy is better than later.

PVNS can be treated arthroscopically in the ankle as elsewhere. Synovial Chondromatosis is rare in the ankle, but is treated along standard arthroscopic lines.

Other arthritides have been described such as gonarthritis, Crohn's gout, chondrocalcinosis and are treated with arthroscopic synovectomy.

Infections
Bacterial and fungal infections occur and are best treated with arthroscopic aspiration and synovial biopsy followed by washout and irrigation then appropriate antibiotic therapy.

Degenerative disease
Primary and secondary osteoarthritis can be treated arthroscopically.

Miscellaneous
Arthrofibrosis post fracture or sprain can occur and is satisfactorily treated by arthroscopic resection of the fibrous bands and early physiotherapy.

ARTICULAR SURFACE DEFECTS, LOOSE BODIES AND OSTEOPHYTES
OCD Lesions of the talus - OLT
Osteochondral lesions of the talus as such were first described in 1856 by Monro but Konning coined the term "osteochondritis" when he found similar pathology elsewhere in the body and thought the aetiology was osteonecrosis. Kappis in 1922 first applied the term osteochondritis to the ankle joint.

Berndt and Harty in 1959 postulated a traumatic aetiology and used the term transchondral fracture of the talus. O'Donoghue said the lesions were intra-articular fractures and Campbell and Ranawat felt the cause was ischaemia in 1966. Alexander and Lichtman + Canale and Belding have subsequently lent support to the traumatic aetiology in 1980. However the exact aetiology remains uncertain.

It is certainly a condition which tends to be under diagnosed bearing in mind that talar osteochondritis accounts for 4-10% of all osteochondritides. It affects males more commonly than females and a peak incidence at 20-30-years of age.

The lesions are either posteromedial or anterolateral. If they are posteromedial - 70% are traumatic - are deep and not usually displaced. They are usually caused by inversion of the dorsiflexed foot (torsional impaction) ref. Of the anterolateral lesions - 90% are traumatic - are usually thinner and are more commonly displaced. They are typically caused by inversion of the plantar flexed foot.

Clinically patients present with a history of trauma, pain, swelling, catching, givingway or locking. On examination one may find swelling and tenderness.

The diagnosis is best made by CT or MRI. A classification based on CT correlates better with the arthroscopic findings than the original classification of Berndt and Harty. Zinman and his colleagues found CT to be superior to XR's in diagnosis, but MRI also has been advocated particularly by Dipaoala. Anderson has developed an MRI based classification and found CT to be as good as MRI except in diagnosing grade 1 lesions.

Cheng and Ferkel went on to show CT to be the scan of choice if the diagnosis is known but MRI if it is not. They have also developed an arthroscopic classification.

Treatment of the stage 1& 2 lesions is 6-12 weeks in a cast, but arthroscopy if conservative treatment fails. Stages 3 & 4 lesions are treated arthroscopically immediately.

Results of treatment are good with Loomer showing 80% good or excellent results.

The surgical approach is as follows for acute OLT. They are palpated with a hook. Loose chondral fragments alone are excised but osteochondral fragments are pinned or screwed into the base of the defect whether displaced or undisplaced.

For chronic OLT again palpate with a hook, see if it is loose. Fix it if it is loose and the underlying bone is healthy, if the underlying bone is unhealthy you need to excise the loose fragment and drill the base of the defect. Large areas can be treated by osteochondral graft large.

It has been shown by Buckwalter that penetration of subchondral bone disrupts subchondral vessels, this produces bleeding, a clot and fibrocartilagenous repair. The cells responsible for this enter from the marrow. Significant cartilage defects can be repaired by tissue which grows up drill holes to cover exposed subchondral bone.

The results of arthroscopic treatment of OLT are as good if not better than open surgery i.e. 80% plus.

Osteophytes, loose bodies, and chondral lesions of the ankle
Arthroscopic ankle surgery is also successful other pathologies apart from impingement and OLT. Martin and Ferkel in 1989 reported 71% good/excellent results for OLT lesions, 57% good/excellent results for loose bodies and osteophytes and 12% good/excellent results for DJD.

With loose bodies it is necessary to inspect the posterior compartment and you need to check all the articular surfaces carefully after their removal.

Osteophytes in the ankle are a common condition known as the "anterior kissing lesions" or "Footballers Ankle". It is O'Donoghue in 1966 who reported a 45% incidence in American Football players, there is an even higher incidence of 59.3% in dancers. Patients with "Footballers Ankle" present with pain catching and restricted joint motion (dorsiflexion) and swelling.

Treatment aims to reproduce the normal 60 degree tibiotalar angle. One must be careful to avoid neurovascular injury when performing surgery open or closed. Arthroscopically the borders of the osteophyte are exposed with a 3.5mm soft tissue resector then the bony spurs themselves are removed with burrs. Per operative lateral x-ray prior to completion can be taken to ensure sufficient bony resection, it has been shown that one obtains better results if the patients have isolated spurs than generalised DJD but overall excellent results are achievable.

A classification with grades I-N was described by Scranton, (1-111 treatable arthroscopically) but even grade IV lesions can be addressed arthroscopically. Interestingly talofibular bony impingement can also occur.

Chondral lesions also occur and are usually caused by a sprain or also by an RTA with direct compression of the articular cartilage. The pathologies range from blistering to full thickness flap tears. These lesions are frequently missed because of normal XR in A/E. If such lesions are suspected then ankle arthroscopy is the only sure way to diagnose them with a full examination of anterior and posterior compartments required. Arthroscopic surgery is straight forward resecting chondral flaps to stable base and drill exposed bone to encourage vascular invasion and fibrocartilage formation.

Ankle arthroscopic debridement and lavage parallels that of arthroscopic treatment of DJD in other joints.

Lateral ligament instability
Lateral ligament injury of the ankle is very common; with one person in 10,000 sustaining the injury per day it is the commonest ligament injury seen by surgeons. Repeated lateral ligament injuries interfere with normal daily life and with chronic instability a minor trauma can cause a significant inversion injury with unpredictable outcome.

Surgery to correct lateral ligament instability was described as early as 1949 by Nilsonne who described a peroneus brevis transfer. But it was Brostrom who showed that direct repair of the lateral ligament was possible even years after acute injury and Hamilton reported 93% good or excellent results with a modified Brostrom procedure. With lateral ligament tears it is the anterior talo-fibular ligament fails first, calcaneo fibular ligament rupture is rare. A repair/reconstruction ideally needs to reproduce the ATFL in its anatomic position and this is what a Brostrom or Hamilton procedure does.

The diagnosis of lateral ligament instability is straight forward, there is a history of instability the lateral ligaments are tender and moving the ankle demonstrates excessive inversion and an exaggerated anterior draw test, this is when the foot and talus are translocated anteriorly in the mortis and the amount of anterior movement recorded and compared with the normal side.

Radiographic lateral stress views can be performed applying set forces of inversion. But results of such instability testing can be questionable if the calcaneofibular ligament is intact and these patients still have instability.

Arthroscopically there is ballooning of the anterolateral capsule which appears and feels thinner than normal. One frequently sees scarring of the lateral gutter and syndesmosis with associated loose bodies or ossicles and lateral dome or plafond chondral changes.

Treatment is either an open or closed modified Brostrom repair with three weeks in a below-knee cast then standard physiotherapy. Arthroscopic results are as good as open.

Ankle arthrodesis
An ankle arthrodesis if successful allows a patient to return to work and some sports with a virtually normal gait. Fusion rates have been reported from any series as in the order of 80% and infection occurring in 5-25%. Morgan in 1985 reported a 96% fusion rate with 90% good/excellent results. He maintained the contour of the talar dome, kept the ankle in neutral and used cross-screw internal fixation.

Two years earlier Schneider first described arthroscopic ankle arthrodesis. But it was Morgan who published the first report in 1987. Myerson compared open and closed techniques of ankle arthrodesis with a reported quicker fusion time arthroscopically of 8.7 versus 14.5 weeks theoretically because of the lack of disruption of the soft tissues and therefore a better blood supply to the fusing surfaces. The faster fusion rate was backed up by Ogilvie-Harris who reported an 89% fusion rate arthroscopically with 88% fused by the third post operative month!

The advantages of an arthroscopic arthrodesis are reduced morbidity, shorter Hospital stay, faster fusion rate, better cosmesis and lower complication rates. Against these are long learning curve for the surgeon and theatre staff, it is a longer procedure and requires expensive arthroscopic equipment. Also it cannot correct large varus, or rotational deformities.

The contra-indications for an arthroscopic arthrodesis are >15 Degrees deformity, a previously failed arthrodesis, the presence of infection, RSD and a charcot joint. Mann showed that the best fusion position is with the ankle in neutral, avoiding >10 Degrees plantar-flexion and with the os-calcis in 5 degrees valgus. Also the "Mann" position results in the best gait. You do however lose 70% of your total motion arc with an ankle fusion and tarsal hypermobility is increased 85%.

The arthroscopic technique is to have the standard arthroscopic set up with either invasive or non-invasive distraction. Remove all articular cartilage initially from the talar dome and planfond then the gutters to expose bleeding underlying bone and finally the anterior osteophyte needs removal as this would otherwise resist talar reduction. The fusion is secured with crossed cannulated screws. Screw positioning is arthroscopically assisted and the length of the screws can be image intensifier assisted.

The patients then spend 3 weeks non weight bearing followed by 4-6 weeks partial weight bearing. The screws can be removed later if they are causing pain. A range of 3-12 months has been reported for standard open fusion to occur, this compares unfavourably with the arthroscopic technique. Mann from a multi-centre trial recently demonstrated a 91% fusion and 84% good/excellent results. This fusion rate leaps to 96% if known poor techniques are avoided, e.g. laser, external charley type compression.

This article was specifically written for Chiropody Review and we thank Mr Simon Moyes for the time and trouble he took.

CHIROPODY REVIEW,DECEMBER 1998