Data pertaining to foot and ankle surgical procedures for the calendar years 1997–2006 were extracted from the publicly accessible Medicare Benefits Schedule (MBS) database [
9]. A summary of the item numbers and procedures obtained is provided in Additional File
1. Each item number dataset (consisting of the number of procedures performed by sex, age-group and calendar year) was extracted individually and exported into Microsoft Excel (Microsoft Corp, Redmond USA) for analysis. MBS item numbers for procedures that could not be isolated to the foot and ankle (such as excision of soft tissue tumours, treatment of burns, "generic" surgical items and multilevel orthopaedic surgery) were excluded.
Costs per item number (in Australian dollars) were obtained for the 2006 calendar year only, as the cost data did not encompass the entire assessment period (1997–2006).
To simplify the interpretation of the results, item numbers relating to a similar region of the foot or a specific foot condition were combined into one of the following 12 categories:
(i) toenail: wedge resection, partial resection and total removal of toenails (item numbers 44136, 47904, 47906, 47912, 47915, 47916, 47918);
(ii) foot and ankle trauma: including treatment of dislocations and fractures of the ankle, tarsals, metatarsals and phalanges (item numbers 47063, 47066, 47069, 47072, 47594, 47597, 47600, 47603, 47606, 47609, 47612, 47615, 47618, 47621, 47624, 47627, 47630, 47633, 47636, 47639, 47642, 47645, 47648, 47651, 47654, 47657, 47663, 47666, 47672, 47678);
(iii) lesser toes: including primary and secondary repair of flexor and extensor tendons, tenotomy, correction of clawtoes, hammertoes and hyperextension deformity (item numbers 49800, 49803, 49806, 49809, 49812, 49848, 49851 and 50345);
(iv) ankle: including diagnostic arthroscopy, arthroscopic surgery, ligamentous stabilisation, arthrodesis, total joint replacement and Achilles tendon procedures (item numbers 49700, 49703, 49706, 49709, 49712, 49715, 49718, 49721, 49724, 49727 and 50312);
(v) first metatarsophalangeal joint (1st MPJ): including excisional arthroplasty, osteotomy, adductor hallucis tendon transfer, prosthetic arthroplasty and arthrodesis for either hallux valgus or hallux rigidus (item numbers 49821, 49824, 49827, 49830, 49833, 49836, 49837, 49838, 49839, 49842, 49845, 49857, 49860 and 49863);
(vi) neuroma: neurectomy for plantar digital neuritis (item number 49866);
(vii) amputations: digital, transmetatarsal, Syme (item numbers 44338, 44342, 44346, 44350, 44354, 44358, 44359, 44361, 44364);
(viii) clubfoot: including posterior release, medial release or combined postero-medial release (item numbers 50315, 50318, 50321, 50324, 50327, 50339 and 50342);
(ix) heel: including excision of calcaneal spur and plantar fasciotomy (item numbers 49818 and 49854);
(x) rearfoot: including triple arthrodesis and subtalar joint arthrodesis (item numbers 49815 and 50118);
(xi) lesser metatarsophalangeal joints: synovectomy of metatarsophalangeal joints (item numbers 49860 and 49863);
(xii) tarsal coalition and congenital vertical talus (item numbers 50333 and 50336);
To calculate the total number of procedures performed between 1997 and 2006, all item numbers pertaining to bilateral procedures (49824, 49830, 49836, 49838, 49842 and 50327) were considered to represent two individual procedures. However, when calculating total costs for the year 2006, the cost for each item (unilateral or bilateral) was used.
To evaluate trends in the total number of procedures per year between 1997 and 2006, both absolute and adjusted figures were calculated, as approximately two million additional people were enrolled in Medicare over the assessment period. To determine the number of procedures relative to the number of people enrolled, the number of eligible people for the last quarter of each year was extracted from the database, and the number of procedures was expressed per 100,000. However, because the database does not report sex or age of those enrolled, it was not possible to determine whether trends over time differed according to these characteristics.