Total talar replacement with a novel 3D printed modular prosthesis for tumors

Figures & data

Figure 1 The preoperative images.

Notes: (A–C) An extensive osteolytic lesion in the talus. (D) Bone scan revealed an increased uptake around the ankle.

Figure 2 The prosthesis design.

Notes: (A) Anterolateral view of the installed prosthesis, with the sinus tarsi completely filled (red arrow). (B) Top view of the lower modular component of the prosthesis placed on the calcaneus. Pre-drilled holes for screws can be seen. (C) Mediolateral view of the installed prosthesis showing the direction of the screw fixation (not the length of screws). The sinus tarsi is completely filled (red arrow).

Figure 3 The models and the finished product.

Notes: (A, B) Models of the prosthesis and adjacent bones were printed and tested to verify our plan before the final production. Anterolateral view of the installed prosthesis, with the sinus tarsi completely filled (red arrow). (C–F) The three-dimensional printed press-fit modular prosthesis. The lower modular component (E, F), with porous structures on the bottom to facilitate subtalar arthrodesis, is made of titanium alloy. The upper modular component (C) is made of ultra high molecular weight polyethylene (UHMWPE). (G) The installed prosthesis fits well to the calcaneus and navicular bone. The gap (green arrow) is designed for easy separation of the two modular components. The hole (yellow arrow) is predrilled for fixation of the talonavicular joint, but it was not fixed during the surgery in order to obtain better foot function.

Figure 4 The intraoperative pictures.

Notes: (A, B) After the removal of the talus through anterior approach, the modular prosthesis was inserted and fixed to the calcaneus. (C) The en bloc resected talus was almost identical to the three-dimensional printed model of the prosthesis of the talus.

Figure 5 The postoperative roentgenographs.

Note: (A, B) The modular prosthesis and the screws are in good position.

Figure 6 Standing appearance.

Note: (A) Dorsiflexion/plantarflexion (B, C) around 6 months after total talar replacement with the three-dimensional printed modular prosthesis in the right foot.

Figure 7 Follow-up radiographs 6 months after surgery.

Note: (A, B) The prosthesis is well positioned, and no abnormalities are noted.

Table 1 Treatment techniques and outcomes for total talar replacement

Author	No of talus	Etiology	Type of prosthesis	Fixation	Follow-up (months)	Preoperative assessment	Final assessment	Notes
aStevens et al,^Citation16 2007	1	Trauma	Cobalt-chrome; unibody; anatomic	Porous coating helped soft tissues ingrowth	48	–	Dorsiflexion: 5° Plantar flexion: 20° AOFAS: 97	None
aGadkari et al,^Citation12 2013	1	Trauma	Cobalt-chrome; unibody; anatomic	Porous coating helped soft tissues ingrowth	264	–	Dorsiflexion: 5° Plantar flexion: 20° Eversion: 0° Inversion: 0° AOFAS: 75	Stiff hindfoot; Mild valgus foot; Difficulty walking on uneven terrain; Prosthesis slightly plantar flexed but still stable
Tsukamoto et al,^Citation13 2010	1	Revision after TAA	Aluminum-ceramic; unibody; anatomic	A fixation peg into the calcaneus	24	–	Dorsiflexion: 15° Plantar flexion: 10° JSSF-RAFA: 65	None
Angthong^Citation14 2014	1	Trauma	Metallic; unibody; anatomic	None	4.6	Dorsiflexion: 0° Plantar flexion: 0° Eversion: 0° Inversion: 0° VAS-FA: 6.0 SF-36: 19.3	Dorsiflexion: 5° Plantar flexion: 16° Eversion: 13° Inversion: 10° VAS-FA: 57.5 SF-36: 73.7	None
Taniguchi et al,^Citation10 2015	55	Osteonecrosis	Aluminum-ceramic; unibody; anatomic	None	Average: 52.8 Range: 24–96	Dorsiflexion: 0.5° ± 3.7° (−8°−7°) Plantar flexion: 43.7° ± 8.3° (32°–60°) JSSF-AHF: 43.1 ± 17 (11–68)	Dorsiflexion: 5.4° ± 4.9° (0°–17°) Plantar flexion: 32.0° ± 8.9° (17°–55°) JSSF-AHF: 89.4 ± 8.4 (76–100)	OS of distal end of tibia: 44%; OS of the navicular: 9%; OS of the calcaneus: 35%
Ando et al,^Citation15 2016	1	Osteonecrosis	Aluminum-ceramic; unibody; anatomic	None	24	Dorsiflexion: 0° Plantar flexion: 20° AOFAS: 45	Dorsiflexion: 20° Plantar flexion: 40° AOFAS: 90	None
Ruatti et al,^Citation11 2017	1	Trauma	Metallic; unibody; anatomic	Hydroxyapatite coating and two screws in two directions for subtalar arthrodesis	24	AOFAS: 11 SF-36: 17	Dorsiflexion: 10° Plantar flexion: 40° AOFAS: 77 SF-36: 82	None
Tracey et al,^Citation17 2018	14	Osteonecrosis	Nickel-plated cobalt; unibody, 3D-printed; anatomic	None	Average: 20.5 weeks Range: 0.86–57.4 weeks	Talar arc length: 36.5 ± 5.89 mm Talar height: 24.73 ± 2.60 mm Talar width: 35.11 ± 4.28 mm Tibiotalar alignment: 91.92° ± 3.25° Talar tilt angle: 2.84° ± 2.26° Boehler’s angle: 39.01° ± 4.7° Talar declination angle: 24.9° ± 10.06° Meary’s angle: 10.49° ± 9.08°	Talar arc length: 40.08 ± 3.81 mm, P = 0.071 Talar height: 29.06 ± 3.26 mm, P < 0.01 Talar width: 35.69 ± 3.31 mm, P = 0.69 Tibiotalar alignment: 90.41° ± 2.11°, P = 0.16 Talar tilt angle: 1.15° ± 1.31°, P = 0.03 Boehler’s angle: 39.1° ± 4.44°, P = 0.96 Talar declination angle: 22.8° ± 5.27°, P = 0.5 Meary’s angle: 5.03° ± 4.62°, P = 0.59	None
Current Study	1	Tumor	UHMWPE and titanium alloy; modular, 3D-printed; anatomic, but with sinus tarsi filled	3D-printed porous structures and screws in three directions for subtalar arthrodesis	6	Dorsiflexion: 15° Plantar flexion: 45° Eversion: 25° Inversion: 25° AOFAS: 73 MSTS: 19	Dorsiflexion: 10° Plantar flexion: 30° Eversion: 5° Inversion: 10° AOFAS: 91 MSTS: 26	Delayed wound healing

Note:

a Stevens et al and Gadkari et al reported the same patient with different time of follow-up.

Abbreviations: 3D, three dimensional; AOFAS, American Orthopedic Foot and Ankle Society Score; JSSF-AHF, Japanese Society for Surgery of the Foot ankle-hindfoot scale; JSSF-RAFA, Japanese Society for Surgery of the Foot Rheumatoid Arthritis Foot and Ankle Scale; MSTS, Musculoskeletal Tumor Society score; OS, osteosclerosis; SF-36, Short-Form-36; TAA, total ankle arthroplasty; UHMWPE, ultra high molecular weight polyethylene; VAS-FA, Visual-Analog-Scale Foot and Ankle.

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