# Recent Advances in Myoelectric Control for Finger Prostheses for Multiple Finger Loss
## 5 Ooseointegrated Implant Retained Myoelectric Prosthesis  
Retention is one of the key factors in the success of a myoelectric finger prosthesis for functions such as grasping, carrying, and holding [50]. A friction or adhesive-retained finger prosthesis cannot provide adequate retention. Bone-anchored osseointegration was originally investigated by the Swedish dentist [PERSON] [51]. An osseointegrated implant retained finger prosthesis offers better retention and helps in different functions [52; 53]. Figure 5 shows implants in a finger bone used for the retention of finger prostheses. In two cases, dental implants were placed in the finger bone to retain the silicone prosthesis. In case 1 (Figure 5a,b), a single implant of 5 mm in diameter \(\times\) 17 mm in length (Oseso Speed, Astra Tech, Molndal, Sweden) was placed in the bone inside the medullary canal with an insertion torque of 40 Ncm for the thumb for single finger loss, whereas in case 2 (Figure 5c,d), three implants of the same size and same insertion were placed on each middle, ring, and little finger thumb for multiple finger loss. Radiographs were taken to verify the position of the implant. Customized metal abutments were fabricated to aid the retention of the silicone prostheses. The mode of retention of the silicone prostheses was friction retained with the metal abutment.  
Figure 5: Implants placed in finger bones for the retention of finger prostheses: (**a,c**) implants in finger bones in an X-ray and (**b,d**) implants in finger bone clinically.  
Finger bone implants also help to reduce the prosthesis failure rate [54]. In addition, osseointegrated implants improve functionality, durability, and freedom of movement in the prosthesis, as well supporting vibrotactile and pressure feedback secondary to osseoperception [55; 56; 57; 58]. Ossoseintegration considers many complications and restrictions inherent to socket-based prostheses, particularly among patients with compromised soft tissue envelopes (e.g., decreased tissue compliance, history of skin grafting, persistent ulceration, or wounds, underlying heterotopic bone, painful neuromons) or a short residual limb [59]. It also eliminates issues related to socket fit and signal transduction between the myositis and the electrodes, improving the efficiency of these devices.  
Excellent development in osseointegration arises from the incorporation of motors-sensory devices into the implant itself [59]. An example of such a device is e-OPRA (Integrum, Sweden), which contains a bidirectional interface using electrodes integrated with the device to improve control of the osseointegrated prosthesis. Currently, clinical trials are being conducted on the e-OPRA device in the USA and are expected to complete by January in 2023 [55]. It has been shown that promising results with more reliability and precision for implanted electrodes than surface electrodes can be found among transhumeral amputees [60; 61]. [PERSON] et al. [62] studied grip control and motor coordination in three transhumeral amputees with the e-OPRA device. The synergy between bone-anchored devices, advanced neuromuscular interfaces, and targeted muscle reinnervation can significantly improve the sensory and motor function of advanced prostheses.  
The main limitation of the above techniques for finger prostheses is that they cannot permit active pronation, supination, flexion, and extension. The use of an implant in the finger bone can aid the retention of myoelectrically controlled finger prostheses regarding finger movements.