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EP-4021321-B1 - EXTERNAL DISTRACTOR AND ADJUSTMENT DEVICE FOR USE IN SUCH A DISTRACTOR

EP4021321B1EP 4021321 B1EP4021321 B1EP 4021321B1EP-4021321-B1

Inventors

  • STRUIK, Thijmen
  • LAFEBER, Floris Paulus Jacobus Gerardus
  • CLOOSTERMANS, Vincent Marianus
  • LINDENHOVIUS, KARIANNE HILDE

Dates

Publication Date
20260506
Application Date
20190826

Claims (15)

  1. Adjustment device (3) for an external distractor (1) arranged to gradually enlarge the distance between a first bone part (100a) and a second bone part (100b), wherein the distractor (1) comprises a first connection device (10a) and a second connection device (10b), wherein the first connection device (10a) is arranged to be connected to the first bone part (100a) with at least one first bone pin (11a) and wherein the second connection device (10b) is arranged to be connected to the second bone part (100b) with at least one second bone pin (11b), wherein the adjustment device (3) is to be arranged between the first and second connection devices (10a,b) for adjusting the distance between the first and the second connection devices (10a,b) along an adjustment axis (A,B), wherein the adjustment device (3) comprises a tubular base body (33) arranged to be coupled to the first connection device (10a), an extension tube (31) arranged to be coupled to the second connection device (10b) and an adjustment mechanism (4) for moving the extension tube (31) with respect to the base body (33) along the adjustment axis (A,B), wherein the adjustment mechanism (4) comprises a rotatable adjustment ring (4) for moving the extension tube (31) upon rotation of the adjustment ring (4) around the adjustment axis (A,B), wherein the adjustment mechanism (4) further comprises at least one spring member (5) engaging the adjustment ring (4) for preventing unintended activation of the adjustment mechanism (4), wherein the adjustment ring (4) is movable between a locked position, wherein rotation of the ring (4) is prevented, and an unlocked position wherein the ring (4) is rotatable, wherein the spring member (5) is arranged to urge the adjustment ring (4) towards the locked position, wherein the adjustment ring (4) is movable along the adjustment axis (A,B) between the locked and unlocked positions, characterised in that the adjustment mechanism (4) and the adjustment ring (4) comprise a cooperating groove-notch mechanism comprising at least one groove (34) and one corresponding notch (44), wherein rotation of the adjustment ring (4) is prevented when the notch (44) is received in the groove (34).
  2. Adjustment device according to claim 1, wherein the adjustment ring (4) comprises an inner ring member (41) and an outer ring member (42), wherein the outer ring member (42) is arranged to be engaged by a user, wherein the inner ring member (41) and outer ring member (42) are coupled in a substantially form locked manner such that rotation of the outer ring member (42) rotates the inner ring member (41), wherein the outer ring member (42) is movable with respect to the inner ring member (41) along the adjustment axis (A,B).
  3. Adjustment device according to claim 2, wherein the inner ring member (41) and the extension tube (31) are provided with cooperating threading (6) for moving the extension tube (31) upon rotation of the inner ring (41), and/or wherein the spring member (5) is arranged between the inner and outer ring member (41, 42).
  4. Adjustment device according to any of the preceding claims, wherein the spring member (5) is arranged to urge the notch (44) in the groove (34) upon alignment of the notch (44) and the groove (34).
  5. Adjustment device according to any of the preceding claims, wherein the adjustment mechanism (4) is arranged to disengage the notch (44) from the groove (34) when moving the adjustment ring (4) along the adjustment axis (A,B) from the locked to the unlocked position.
  6. Adjustment device according to any of the preceding claims, wherein the groove-notch mechanism has an asymmetric configuration, wherein the shape of the groove (34) and/or the notch (44) in a first rotation direction (I) of the adjustment ring (4) is different from the shape of the groove (34) and/or the notch (44) in the opposite rotation direction (II) of the adjustment ring (4).
  7. Adjustment device according to claim 6, wherein the groove (34) and/or notch (44) is U- or V-shaped, having a base (34c) and two sidewalls (34a,b) extending therefrom, wherein the angles of the two sidewalls (34a,b) are different.
  8. Adjustment device according to any of the claims 1 to 7, wherein the adjustment ring (4) comprises a notch (44) protruding from its lower surface (49).
  9. Adjustment device according to any of the claims 1 to 8, wherein the adjustment mechanism (4) comprises a plurality of notches (44) and/or grooves (34).
  10. Adjustment device according to at least claim 2, wherein the outer ring member (42) is provided with the notch (44).
  11. Adjustment device according to any of the preceding claims, wherein the extension tube (31) comprises an inner tube (31) and an outer tube (32) movable with respect to the inner tube (31), wherein the adjustment mechanism (4) is arranged to move the outer tube (32) with respect to the base body (33), wherein the extension tube (31) further comprises a damping mechanism, such as a spring member, for damping the relative movement of the inner tube (31) and the outer tube (32).
  12. Adjustment device according to any of the preceding claims, wherein the spring member (5) is arranged to increase the rotational force needed to rotate the ring (4) to such an extent that manually operating the ring (4) is not possible.
  13. Adjustment device according to any of the preceding claims, wherein a tool (90) is required for engaging and operating the adjustment mechanism (4).
  14. Combination of an adjustment device (3) according to claim 12 or 13 and a tool (90) cooperating with the ring (4) for rotating said ring (4).
  15. External distractor (1) arranged to gradually enlarge the distance between a first bone part (100a) and a second bone part (100b), wherein the distractor (1) comprises a first connection device (10a) and a second connection device (10b), wherein the first connection device (10a) is arranged to be connected to the first bone part (100a) with at least one first bone pin (11a) and wherein the second connection device (10b) is arranged to be connected to the second bone part (100b) with at least one second bone pin (11b), wherein the distractor (1) further comprises an adjustment device (3) according to any of the preceding claims 1-13, wherein the adjustment device (3) is arranged between the first and second connection devices (10a,b) for adjusting the distance between the first and the second connection devices (10a,b) along an adjustment axis (A,B), wherein the tubular base body (33) of the adjustment device (3) is coupled to the first connection device (10a) and the extension tube (31) of the adjustment device (3) is coupled to the second connection device (10b).

Description

The present invention relates to an adjustment device for an external distractor arranged to gradually enlarge the distance between a first bone part and a second bone part, wherein the distractor comprises a first and a second connection device, wherein the first connection device is arranged to be connected to the first bone part with at least one first bone pin and wherein the second connection device is arranged to be connected to the second bone part with at least one second bone pin, wherein the adjustment device is to be arranged between the first and second connection devices for adjusting the distance along an adjustment axis, or other properties such as resilience, between the first and the second connection devices, wherein the adjustment device comprises a tubular base body arranged to be coupled to the first connection device, an extension tube arranged to be coupled to the second connection device and an adjustment mechanism for moving the extension tube with respect to the base body along the adjustment axis, wherein the adjustment mechanism comprises a rotatable adjustment ring for moving the extension tube upon rotation of the adjustment ring around the adjustment axis. Such an external distractor is for instance described in WO2017/016611 A1. In this known system, two connection devices are coupled to a patient using respective bone pins at a mutual distance, for instance spanning a joint such as the knee. The connection devices are coupled using an adjustment device, and typically one or more ball joints to allow movement between the connection devices, wherein the adjustment device is arranged to increase the distance, preferably in a gradual manner, between the connection devices along the adjustment axis and therewith establishing distraction of a joint. Additional components such as a connection rod may be provided between the connection devices. Such an adjustment device typically comprises a telescopic tube assembly, wherein an extension tube is movable with respect to a tubular base body. Adjustment, i.e. extension, of the extension tube can be achieved by manipulating an adjustment ring. The ring and the extension tube may for instance be provided with cooperating threading such that rotation of the ring leads to movement of the extension tube with respect to the base body along the adjustment axis. The extension tube is preferably aligned with the adjustment axis, which is also aligned with the axis of movement of the two bone parts as mentioned above. An improved distraction process may be obtained when the distraction device comprises a resilient member such as a spring. US patent publication No. 6,030,386 discloses a telescopically adjustable strut to be used in conjunction with an external orthopaedic fixator. US patent publication No. 8,574,232 B1 discloses an adjustment device according to the preamble of claim 1. It is a goal of the present invention, next to other goals, to provide an improved external distractor - in terms of for instance safety and/or user-friendliness. This goal, amongst other goals, is met by an adjustment device for an external distractor according to appended claim 1. The adjustment mechanism comprises a spring member engaging the adjustment ring. The spring member is arranged for preventing unintended, i.e. accidental, activation of the adjustment mechanism, or preventing adjustment. During distraction, the distance between the connection devices, and thereby for instance the bones comprising a joint, is preferably gradually and incrementally increased. This adjustment is typically done by the the end-user, e.g. a clinician or patient. The adjustment mechanism is manually operable, in specific cases with a dedicated tool or key for adjusting the setting. At the same time, accidental or unintended adjustment during clinical application of the distractor needs to be prevented. The spring member prevents this accidental rotation, such that the safety of the distractor is improved. The spring member hereby engages the adjustment ring such that accidental rotation of the adjustment ring is prevented. The spring member may for instance be coupled between the adjustment ring and distraction device, for instance the base body thereof, to increase the rotating resistance of the adjustment ring. Rotation of the ring then requires an increased rotational force, e.g. torque, such that activation of the adjustment mechanism due to low rotational forces during common daily activities is prevented. The spring member may for instance be a leaf spring engaging the adjustment ring. Generally, it is preferred if the spring member is arranged to prevent rotation of the adjustment ring. The spring member may be arranged to increase the rotational force, e.g. torque, needed to rotate the ring, in particular to such an extent that manually operating the ring is not possible. It is then preferred if the ring is arranged to cooperate with a tool for rotating the ring. The