Joint Manipulation: Toward a General Theory of High-Velocity, Low-Amplitude Thrust Techniques
SOURCE: J Chiropractic Humanities 2017 (Mar); 20 (1): 1–9
Andrew S. Harwich, D.O.
The Bridge House Practice,
154 Caledonian Road,
Kings Cross, London, UK, N1 9RD
Objective The objective of this study was to describe the initial stage of a generalized theory of high-velocity, low-amplitude thrust (HVLAT) techniques for joint manipulation.
Methods This study examined the movements described by authors from the fields of osteopathy, chiropractic, and physical therapy to produce joint cavitation in both the metacarpophalangeal (MCP) joint and the cervical spine apophysial joint. This study qualitatively compared the kinetics, the similarities, and the differences between MCP cavitation and cervical facet joint cavitation. A qualitative vector analysis of forces and movements was undertaken by constructing computer-generated, simplified graphical models of the MCP joint and a typical cervical apophysial joint and imposing the motions dictated by the clinical technique.
Results Comparing the path to cavitation of 2 modes of HVLAT for the MCP joint, namely, distraction and hyperflexion, it was found that the hyperflexion method requires an axis of rotation, the hinge axis, which is also required for cervical HVLAT. These results show that there is an analogue of cervical HVLAT in one of the MCP joint HVLATs.
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Conclusions The study demonstrated that in a theoretical model, the path to joint cavitation is the same for asymmetric separation of the joint surfaces in the cervical spine and the MCP joints.
Key Indexing Terms: Manipulation, Chiropractic, Manipulation, Osteopathic, Biomechanical Phenomena
From the FULL TEXT Article
High-velocity, low-amplitude thrust (HVLAT) techniques are widely used in manual therapies and nearly always produce a “cracking” noise. This is considered a cavitation event [1, 2] for the metacarpophalangeal (MCP) joint and is produced by the sudden separation, or “gapping,” of the joint surfaces. In clinical practice, the force to do this is applied manually. It is assumed that the event is the same mechanism in both spinal and peripheral joints, as it involves the same types of structures. For example, similar characteristics were found for joint noises (ie, “cracks”) in both the MCP joint and the cervical apophysial joint.  In addition, it was found that gapping occurred in lumbar adjusting procedures.  Various terms have been used for the lesion that is treated with HVLAT.  In this paper, the term “joint dysfunction” will be used.
One way to try to better understand the joint dysfunction that is treated with HVLAT is to analyze in detail the kinematics of the thrust procedure used in clinical practice that produces joint gapping. Following the reverse path of those kinematics should then reveal the path to the lesioned state.
There appear to be problems with describing the manipulative technique unambiguously: one description of the spinal manipulative thrust technique6 focused on “end feel” for what has been called the preload phase of the maneuver produced by combinations of applied movements.  However, these combinations are only hypothesized, and the numerous variations of the positioning prior to delivery of the thrust (eg, it is not agreed whether the target joint should be in flexion or extension) are based on a prescriptive rationale that has not been verified by proper testing. For example, the direction of the thrust on a target joint would appear to depend on the therapist’s desire to either increase or decrease tension on unspecified joint structures. Hing et al.  stated that HVLAT can be performed on the same joint in at least 3 directions following the methods described in the literature.  The authors failed to explain how the target joint is gapped in 2 of these directions (ie, “upslope” and “downslope”), if that is an immediate aim of the manipulation, since the thrust is parallel to the joint plane.