The Keystone Flap Technique to Solve Orthopaedic Defects of the Lower Limb from the Inguinal Region to the Dorsum of the Foot

The closure of major defects of the groin in orthopaedic management relate to explorations or ORIF repairs of the neck of the femur with access to the pelvic rim usually following motor vehicle accidents. This case had a 10 × 15 cm defect, and this becomes part of the orthopaedic management after any ORIF procedure needing cover. The use of loco-regional flaps and/or the use of a rectus island flap (Robbins, Aust N Z J Surg 49(5):527–530, 1979) is a standard method of closure of groin defects measuring more than 10 × 15 cm. The complicated island flap reconstruction, though time consuming, is easily replaced by the use of a Keystone flap of the anterior thigh based on the L1/L2 dermatomes. It simply means that the basic overall principles can be extended (Behan, Atlas of keystone reconstructive technique in melanoma management. Springer, Cham, 2023) when closing similar defects for orthopaedic issues when integumentary cover is necessary. In essence, the keystone groin flap (Behan, Atlas of keystone reconstructive technique in melanoma management. Springer, Cham, 2023) is simply raised on the fascial base by dividing down the cutaneous margins of the lateral thigh dividing tensor fascia lata longitudinally, then transversely completes the suprapatellar incision and the delineation of the island flap. The incision is completed up the medial side toward the groin dividing the fascia, thus creating the island of tissue with a fascial substrate. It is quite amazing how the floppiness of the anterior thigh tissue thus divided can move up to 10 cm in slide which is more than enough to close integumentary defects which also can be applied orthopaedically for any groin defects measuring up to 10 × 15 cm but when divided distally, advancement, rotation or transposition of the distal limits of the flap are ideal for closure of amputation sites, with intact protective somatic sensation, an essential requirement in all amputation reconstructive surgical procedures to avoid future trophic ulceration. This compares favourably with the long duration and time consuming stress of microvascular free flaps as itemised in the AJOPS article by Aggarwala et al. (AJOPS 7(1):89290, 2024) in relation to amputation closures using the profunda artery perforator flap. The most important aspect of this technique in amputation stump closure is the flap repair that is sensate. It is wrong in principle to have a weight bearing surface no matter what the size in a weight bearing site where protective sensation and the resultant trophic ulceration can be minimised—the one drawback of a free flap reconstruction. This needs no elaboration. So, in summary the stump is trimmed and reduced in length, the soft tissue closure covers the bone, protective sensation is retained and the mechanisms are in place for an amputation with its usualy covers of silicone sleeves and cotton or woollen layers. In summary, a sensate flap is the ultimate ideal for long-term clinical stability. The acronym P.A.C.E.S. is a synoptic overview of the characteristics of the keystone. The surgical delineation of the keystone design divides temporarily sensory input to the integument which recovers. Aesthetically, it is almost a perfect match compared with microsurgery. Complications from a vascular strategy point of view are reasonably uncommon if the delineation techniques are followed. Economically, it is a timesaver from the point of view of surgical repair and theatre time and staff monitoring. Like the cutaneous supply across any surgical wound, sensory recovery returns in 2–3 weeks as the same timeframe as the resolution of oedema. It is assumed hypothetically that creating an island flap of the integument but based on suprafascial and infrafascial perforator circulation. Any secondary defects are grafted to avoid tension, if needed.