Vita Yu-Hsien TU, Occupational Therapist and Project Manager,
Sunshine Social Welfare Foundation
Intrinsic contracture in a burned hand can lead to significant functional limitations. It often begins as intrinsic tightness, which, if left untreated, can progress into intrinsic contracture.
In this article, we’ll discuss why paying attention to intrinsic tightness is important, and how to avoid 5 blind spots in the rehabilitation process for overcoming post-burn intrinsic tightness and guarantee the efficiency of our interventions.
What is intrinsic tightness?
Intrinsic tightness involves the shortening of intrinsic muscles, leading to an imbalance between intrinsic and extrinsic hand muscles. Intrinsic contracture is a more severe form of tightness, resulting in an "intrinsic plus" hand posture, characterized by MCP flexion and PIP/DIP extension.
Intrinsic tightness may be caused by:
Scar contracture on the palm of the hand after burns;
Immobilization of the hand in a safe position (MP 70-90 degrees, IP 0 degrees) for too long without any exercises;
Intrinsic muscle fibrosis and tendon adhesion caused by post-burn hand edema.
The characteristic of intrinsic tightness is that when the hand makes a fist (composite flexion of all the finger joints), flexion of MP joints will be more pronounced, while flexion of PIP joints will be limited. Also, in the process of making a fist, the range of MP flexion must be large enough in order for PIP flexion to begin to appear. When the hand makes a hook (MP joints in extension and IP joints in flexion), MP joints cannot achieve extension and PIP joints cannot achieve flexion, which causes MP joints to flex even more.
Because intrinsic muscles (Interossei Muscles and Lumbrical Muscles) mainly produce MP flexion and PIP extension movements, when these muscles are tightened, it will result in the above-mentioned movement patterns and may even lead to MP flexion contracture.
What are the 5 blind spots to avoid when dealing with post-burn intrinsic tightness?
Now that we know what is intrinsic tightness and how it can severely affect hand functions, we need to prevent it or, if it is already present, identify and treat it. But sometimes the following 5 blind spots can get in the way of our efforts.
Blind spot 1: Ignoring edema, or ignoring joint movement restriction caused by edema or bandaging from dressings.
Post-burn hand edema may develop when the hands are injured, but also even when the hands are not directly injured, due to systemic edema. During the acute stage, various medical interventions, tubes, and bandages may contribute to hand edema, which often goes unnoticed. This oversight can lead to intrinsic muscle fibrosis and tendon adhesion, ultimately causing intrinsic muscle tightness.
Also, the swelling of the hand caused by edema may end up limiting joint movement. This can also be caused by thick, bulky dressings. While joint movement restriction can be initially explained by the necessity of dressings or the presence of edema, prolonged restriction can lead to intrinsic tightness in the hand over time.
Blind spot 2: Just because there’s PIP flexion limitation, it doesn’t mean it is intrinsic muscle tightness.
At first glance, it may be thought that PIP flexion limitation is caused by intrinsic muscle tightness, but it’s not necessarily always the case. PIP flexion limitation may also be caused by scar contracture on the dorsal side of fingers. The Bunnel Test can be used to confirm. If tightness felt by the patient when making a fist is greater than the tightness felt when making a hook, then PIP flexion limitation is mainly due to the restriction caused by the scar on the back of the finger.
Blind spot 3: Focusing on exercises involving making a fist to address insufficient PIP flexion
Intrinsic muscle tightness is marked by excessive MP flexion and inadequate PIP flexion. Consequently, patients and caregivers may express significant concern regarding the limited PIP flexion and may want to emphasize frequent practice of fist movement. However, it's essential to note that when intrinsic muscles are tight, making fist movements continuously is not advisable. This action can inadvertently reinforce MP flexion and exacerbate the existing tightness in intrinsic muscles. As intrinsic muscle tension intensifies, PIP joints are more likely to extend, exacerbating the issue of insufficient PIP flexion.
Blind spot 4: Mistaking finger PIP flexion as the highest priority of treatment
Intrinsic muscle tightness is characterized by excessive MP flexion and insufficient PIP flexion. However, determining the priority for addressing joint activities is essential. While it might seem logical to tackle finger PIP flexion issues first, the root of intrinsic muscle tightness symptoms actually lies in the tightness of MP flexion. By increasing MP extension, we effectively lengthen the passive extension of intrinsic muscles and enhance their ability to stretch actively.
Once intrinsic muscles are relaxed and no longer exert continuous extension force on PIP joints, it becomes advantageous to focus on increasing PIP flexion while keeping MP joints extended. Therefore, the recommended approach is to start by improving MP extension, followed by increasing PIP flexion, and ultimately enhancing PIP flexion with MP joints in an extended position. This sequence optimally addresses the issue of intrinsic muscle tightness.
Blind spot 5: Only focusing on joint range of motion and overlooking the importance of muscle balance.
Joint range of motion limitation is an obvious and easily identifiable issue, but in addition to focusing on range of motion, strengthening muscle power is also crucial. Because intrinsic muscle tightness results from an imbalance between extensor and flexor muscles, by strengthening the weak muscles, it is possible to improve the movement of MP and PIP joints. Therefore, the focus of intervention should also be on strengthening the FDS and FDP muscles to promote IP flexion and strengthening the EDC muscles to promote MP extension.
Conclusion
In conclusion, addressing intrinsic tightness in a burned hand is of paramount importance to prevent the progression into intrinsic contracture, which can severely limit hand function. In this article, we've explored the significance of recognizing and managing intrinsic tightness, as well as the 5 blind spots to avoid when dealing with post-burn intrinsic tightness.
Intrinsic tightness results in a disparity between intrinsic and extrinsic muscles, leading to imbalanced hand movements. To effectively address intrinsic tightness, it's crucial to avoid certain blind spots. These include overlooking the impact of edema and joint movement restrictions caused by bandages, recognizing that PIP flexion limitation may not always be due to intrinsic muscle tightness, refraining from exercises solely focusing on making a fist to address insufficient PIP flexion, and understanding that the priority should be on improving MP extension, not just finger PIP flexion. Moreover, achieving muscle balance by strengthening specific muscle groups such as the FDS, FDP, and EDC is also essential to improve hand function.
In essence, a comprehensive approach that considers both range of motion and muscle strength is crucial when dealing with intrinsic tightness. By addressing these aspects effectively, we can enhance the quality of care and the potential for restoring functional hand mobility in individuals with intrinsic muscle tightness.