Liu Jun-da (刘骏达), Li Jian-hua (李建华), Hu Bing-lin (胡炳麟), Shao Sheng (邵盛), Zhang Hao (张昊)

1 Department of Tuina, Ningbo Municipal Hospital of Traditional Chinese Medicine, Zhejiang Province, Ningbo 315010, China

2 Department of Tuina, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai 200437, China

Abstract

Keywords: Tuina; Massage; Tendon-bone Balance; Atlantoaxial Joint; Tendon Off-position; Joint Subluxation; Spinal Fine Adjusting; Chiropractic

Tendons and bones are the important components of joints in the human body. TheHuang Di Nei Jing(Yellow Emperor’s Classic of Internal Medicine) not only discusses the relationship between tendons and bones,but also puts forward the health concept of ‘aligned bones with soft tendons’ which is the prototype of the theory of ‘tendon-bone balance’. The human atlantoaxial joint (AAJ) is a composite joint composed of tendons and bones, and its function depends on the‘tendon-bone balance’ of the joint. Multiple reasons can break the ‘tendon-bone balance’, which can easily lead to atlantoaxial subluxation (AAS), manifesting as head and neck motor dysfunction, dizziness, headache,and even abnormal sensation in the limbs, also known as ‘atlantoaxial joint misalignment’ and ‘atlantoaxial instability’[1-2]. Given that most people have different degrees of atlas and axis structural variation[3], the disease has remained controversial since its discovery.The current mainstream view argues that the diagnosis of AAS is meaningful only if the patient has both symptoms and imaging manifestations. In China,imaging data are usually collected in the mouth-open position photographic method, but the criteria for positivity have not been unified so far[4]. The textbook ofTuina Therapeuticsproposes a relatively eclectic standard: an atlanto-odontoid gap >2 mm in adults,>3 mm in adolescents, or atlanto-odontoid gap >2 mm on both sides was the specific imaging feature[1].Adolescents with AAS are numerous and typically symptomatic, with the main etiology being mechanical injury and congenital anatomical abnormalities of the cervicocranial junction, and also a small number triggered by inflammation of the pharynx[2]. In the past,AAS was once thought to be a disease specific to adolescents, and adult patients with neck discomfort or neurological symptoms such as dizziness often ignored the problem of AAS, so some patients did not achieve the expected results after being treated as ‘cervical spondylosis’. In recent years, some scholars have compared the mouth-open X-ray of adult cervical spondylosis patients with the above symptoms with that of healthy adults, and found that the number of patients with distorted odontoid process was significantly larger than that of healthy patients[5], which shows that AAS is more common in adult cervical spondylosis patients and should be taken seriously.

Tuina can restore the ‘tendon-bone balance’ of the AAJ more directly than other Chinese medicine therapies through ‘tendon smoothing’ and ‘bone setting’ manipulations. However, the conventional manipulations did not pay attention to the theory of‘tendon-bone balance’, and they lacked safety and effectiveness. Based on this, this article analyzed the pathogenesis of adult AAS from the perspective of‘tendon-bone balance’ in Chinese medicine, discussed the shortcomings of conventional manipulations, and introduced several modified manipulations that have advantages in ‘tendon smoothing’ and ‘bone setting’. It was suggested that tuina practitioners should use these manipulations reasonably according to the theory of‘tendon-bone balance’ in order to improve the clinical efficacy of tuina treatment for AAS.

1 ‘Tendon-bone Balance’ of the AAJ

There is no intervertebral disc between the atlas and axis vertebrae, and the two vertebrae are connected by ligaments to form the atlantoaxial complex joint,including the middle atlanto-odontoid joint and the posterior AAJ on both sides. The atlanto-odontoid joint is the core of the AAJ, with the odontoid process playing a role similar to that of a ‘bearing’. The ligaments connected to it can maintain the stability of the joint as well as participate in its movement. In other words, the atlas and axis vertebrae are the ‘bones’ of the joint; the ligaments attached to the odontoid process constitute the ‘tendons’ of the joint[6], which reinforce the joint and restrain the movement of the atlas and axis vertebrae during motion.

The ‘tendon-bone balance’ of the AAJ includes both exogenous and endogenous balance[7]. The exogenous balance is between the extra-articular stabilizing structures and the vertebral body, including the anterior atlantoaxial ligament, posterior atlantoaxial ligament,posterior longitudinal ligament of the atlantoaxial segment, and the suboccipital, intertransverse,interspinous muscles attached to the atlantoaxial spine.Endogenous balance is essentially dominated by the atlanto-odontoid joint, that is, the balance between the odontoid process and the joint capsule, the apical ligament, the alar ligament, the transverse atlantoaxial ligament, and the transverse-occipital and transverse-pivotal ligaments emanating from its middle.The endogenous balance plays a decisive role in the normal movement of the joint, especially the ‘cruciate ligament’ structure formed by the transverse atlantoaxial ligament, transverse-occipital ligament, and transverse-pivotal ligament, which greatly restricts the posterior movement of the odontoid process and prevents the spinal cord behind the spinal canal from injury. Endogenous balance is the key to atlantoaxial‘tendon-bone balance’, which largely determines exogenous balance. Also, healthy exogenous balance helps to maintain endogenous balance. The exogenous and endogenous ‘tendon-bone balances’ are coordinated, and it is ‘tendon-bone balance’ of the AAJ.

2 ‘Tendon-bone Imbalance’ of the AAJ

In theSu Wen(Essential Questions), there is a discussion on the topic that ‘prolonged standing hurts the bones and prolonged walking hurts the tendons’,suggesting that strain injury is an important cause of tendon and bone disorders. Little attention had been paid to adult AAS and no systematic aetiology had been attributed to it in the past. However, in recent years,some scholars have suggested that old trauma may be another cause of AAS in adults[8]. In clinic, some patients had a history of neck trauma at a young age.Whatever the cause, it can affect the exogenous and endogenous ‘tendon-bone balance’ of the AAJ,resulting in an ‘tendon-bone imbalance’ in the joint.Chinese medicine attributes this pathology to ‘tendon off-position, joint subluxation’. The so-called ‘tendon off-position’ refers to the pathological changes in ligaments and tendons, such as ‘tendon stiffness,tendon distortion, tendon breakage, tendon transposition, tendon loosing, tendon contracture,tendon separation’[7]. The expression ‘joint subluxation’is from theYi Zong Jin Jian(Golden Mirror of the Medical Tradition), which refers to the relative displacement of the atlantoaxial vertebrae and is usually manifested as a change in the position of the odontoid process on imaging. In adults, long-term neck overactivity causes injury to the atlantoaxial ligaments or to the ligaments and tendons of the upper cervical segment. The former directly disrupts the endogenous balance. The latter indirectly causes an endogenous imbalance by disrupting the exogenous balance and damaging the intra-articular ligaments, thus losing the restraint of the vertebral body. That is, ‘tendon off-position’ leads to ‘joint subluxation’. Violent injury to the neck can cause atlantoaxial spine misalignment,which may in turn pull ligaments and tendons and therefore result in its distortion, spasm and relaxation,so ‘joint subluxation’ can also lead to ‘tendon off-position’. It is easy to see that ‘tendon off-position’and ‘joint subluxation’ have a mutual influence relationship: the injured ligaments and tendons will aggravate the AAJ misalignment and the misaligned AAJ will also worsen the injury of ligaments and tendons.This is the ‘tendon-bone imbalance’ of the AAJ.

3 Considerations on Conventional Tuina Treatment of ‘Tendon-bone Imbalance’ in AAJ

From the perspective of ‘tendon-bone balance’, tuina can regulate the exogenous balance of the AAJ through two steps: ‘tendon smoothing’ and ‘bone setting’, and then improve the endogenous imbalance and bring the joints back to a balanced state of ‘aligned bones with soft tendons’. We compiled the steps of conventional manipulations for the treatment of AAS, which basically consist of the ‘tendon smoothing’ manipulations to relax the muscles of the upper cervical segment and the‘bone setting’ technique to extract, extend and rotate.Take the left deviation of the spinous process of the axis as an example. The patient takes a sitting or lying position. Firstly, relax the muscles of the cervico-occipital segment by using the relaxation technique and make the patient's neck slightly flexed.Then the doctor extracts and extends the cervical vertebrae with a little force, with the left hand holding up the lower jaw to rotate the neck left to the maximum angle. The left hand suddenly exerts force to the left to expand the rotation angle of the cervical vertebrae by 5-10°. At the same time, the right thumb presses the left side of the spinous process of the axis and pushes it to the right. The doctor's fingers will feel the joint sliding or there will be a crisp ‘click’ sound,which indicates a successful reset. This tuina technique has been widely spread and has achieved good effects[9-10]. However, as tuina discipline has paid more attention to adult AAS in recent years, the shortcomings of this manipulation are magnified, especially the following questionable points.

3.1 Conventional ‘bone setting’ manipulations lack sufficient safety

The primary issue is the safety of the AAJ rotatory manipulation, which has a lot to do with the unskilled force control and excessive pursuit of popping sound by some doctors. As early as the 1990s, Dickman CA,et al[11]found that the transverse atlantoaxial ligament is most susceptible to rupture injury under rapid shear forces. The sensation of the manipulation among different doctors varies greatly and the AAJ of different patients has very obvious individual differences.Therefore, the teaching of this rotating reduction is still at the stage of being unutterable[12]. There is a lack of reproducible manipulation specifications, and accidents sometimes occur[13].

3.2 Conventional ‘bone setting’ manipulations lack effectiveness

The next issue is the effectiveness of the AAJ rotating reduction. This is closely related to individual differences. Due to safety constraints, the technique must be performed in the cervical extension and forward flexion position, but there is no precise range of cervical forward flexion and the specific joint to be adjusted[14]. Basically, it is based on the doctor's experience and sensation. The lower the cervical spine needed to be adjusted, the greater the flexion angle required. When the patient's cervical flexion angle is greater than the angle needed to adjust the AAJ, the rotating reduction will drive the cervical segment that does not need to be adjusted while resetting the AAJ,which may disperse the force and result in poor efficacy.

3.3 Conventional ‘tendon smoothing’ manipulations lack standardization

In contrast to the ‘bone setting’ manipulations which put forward many points of operation, the conventional manipulations do not put forward any special requirements for ‘tendon smoothing’ manipulations.More commonly, they were described as using one-finger Tui-pushing, digital An-pressing,Rou-kneading, and Tanbo-plucking manipulations to relax the muscles of upper cervical segment[15-16].However, we have found that not all adult AAS patients exhibit tension in the upper cervical segment muscle groups, and further relaxation manipulations in patients with relaxed muscle groups seem to be contrary to the principle of manipulation with appropriate force. Xue HX[12]suggests that the force of the ‘tendon smoothing’manipulations should be related to the location of the disease, with lighter force on the superficial muscle, and progressively increasing the force on the deep tendon and fascia. Yan Jun-tao also proposes the concept of‘gentleness making tendons relaxed and force making tendons strong’ for ‘tendon smoothing’ manipulations.He believes that the manipulations should be a combination of delicacy and force, with the tense part of the muscle being treated gently and the weak part of the muscle being treated with strong force. The manipulation range should be gradually expanding from points to lines and surfaces to achieve the purpose of overall treatment[17]. Long XY,et al[18]directly points out that conventional manipulations do not pay attention to‘tendon smoothing’ and do not lay equal stress on tendon and bone in treatment, and there was an urgent need to develop disciplinary standards.

3.4 Conventional manipulations lack the guidance of‘tendon-bone balance’

In theYi Zong Jin Jian(Golden Mirror of the Medical Tradition), it is emphasized that doctors need to know the condition before treating orthopedic diseases, and the treatment should focus on paying equal attention to tendons and bones[19]. If the focus is on tendon injury,then the ‘tendon smoothing’ manipulations should be mainly applied; if the main focus is on bone injury, then the ‘bone setting’ manipulations should be centered on.However, in the treatment of adult AAS, the conventional manipulations do not target the ‘tendon smoothing’ or ‘bone setting’ manipulation according to the cause of the patient's disease, which is different from the idea of ‘tendon-bone balance’. This may have an impact on the efficacy of the treatment.

4 Improved ‘Bone Setting’ Manipulations Have Greater Safety and Effectiveness

In response to the shortcomings of conventional‘bone setting’ manipulation, many practitioners have begun to use new spinal adjustment manipulations, or try to make improvements on the basis of conventional‘bone setting’ manipulations. The author summarized three representative ‘bone setting’ manipulations,which are worthy of tuina practitioners’ attention.

4.1 Chiropractic medicine

The theoretical system of chiropractic has been well established and standardized, and it is one of the most recognized alternative therapies throughout the world.It believes that ‘subluxation of the vertebral joints’should be the root cause of the neuromusculoskeletal disorders in the body[20], and this is also true for adult AAS. The AAJ is mostly repositioned by the ‘extraction and rotation manipulation’. Take the left deviation of the spinous process of the axis as an example: the patient takes a sitting position and the operator stands behind the patient. Firstly, the operator holds the patient's lower jaw with the left elbow, with the left hand holding the patient's right occiput, and the right thumb on the left side of the spinous process. The patient's cervical spine should be flexed to the left front as much as possible and the left side of the face should be as close to the left as possible, then the left elbow lifts the patient's lower jaw slightly and extracts the cervical spine along the sagittal axis for 10-15 s. The left elbow gently rotates the lower jaw to the left for 5-10°with concerted force and at the same time, the right thumb pushes the spinous process to the right side.When the resetting is successful, the operator mostly will sense a clear popping sound or a sliding sensation under the right thumb, and the patient will feel immediate symptomatic relief. This method was used to treat 64 adult AAS patients with an overall effective rate of 95.3%[21].

4.2 Qing Gong (Qing dynasty palace) bone setting

As a branch of traditional Chinese medicine, the‘Qing Gong bone setting’ manipulation is more prevalent in the north of China. It adopts the ‘non-fixed cervical spine rotating-pulling manipulation’ for treating AAS, which has its own characteristics. The basic operation is as follows. The left-side rotating Ban-pulling manipulation is performed first. The patient takes a sitting position and the operator stands behind the patient. The operator holds the patient's lower jaw with the left elbow and put the left hand on the patient's right occiput, gently lifting upward along the sagittal axis of the cervical spine 2 to 3 times. Then the operator rotates the patient's lower jaw to the left to where there is an obvious obstruction and uses the waist and knees to exert force, quickly lifting the patient's head by the left elbow. It is often accompanied by a series of crisp popping sounds. The same method is performed for the right-side rotating-pulling manipulation. This manipulation does not expand the range of motion of the joint and therefore has a great advantage in terms of safety compared with the conventional Ban-pulling manipulation[22].

4.3 ‘Long's chiropractic’ manipulation

The theoretical system and clinical experience of‘Long's chiropractic’ are relatively well-established. It integrates the conventional manipulation with chiropractic to complement the shortcomings. The‘bone setting’ manipulations are performed in steps according to different atlantoaxial displacements, and thus are more standardized. Take the left deviation of the spinous process of the axis with cervical 2/3 reverse-curvature AAS as an example: firstly, the Kua Jiao Ban-pulling manipulation is used. The patient takes a right-side lying position. The operator puts the left thumb on the left posterior articular eminence of the axis, with the right hand holding the right temporal region. The head of the patient is pulled toward the left posterosuperior direction by 45°. The operator presses the eminence with slight force for 10-15 s by the left thumb, and gently rotates the head 2-3 times by the right hand. The supine pushing manipulation is then given. The patient is asked to take a supine position.The operator's right thumb and index finger are placed on both sides of the spinous process of the axis to fix the vertebrae, and the left hand is used to hold the patient's lower jaw. The operator extracts the neck along the sagittal axis by the left hand while pushing the vertebrae forward with slight force for 3-5 s by the right hand. Finally, the supine head rotating manipulation is performed. The patient continues to take the supine position. The operator holds the patient's occipital area by the left hand and holds the patient's mandible by the right hand, tilting the patient's head ≥30°, turning ≤30°to the left, and flashing upward 2-3 times, tilting up≤20°, turning ≥30° to the left, and flashing upward 2-3 times to the left posterior. One or more of the above operations need to be selected targeting the patient's signs, symptoms and imaging data. Proficiency in manipulation can lead to better efficacy[23-24].

The above three ‘bone setting’ manipulations have been improved in safety and effectiveness compared with the conventional Ban-pulling manipulation, but low risk is not the same as no risk. Even with the use of improved ‘bone setting’ manipulations, medical accidents still occur[25], mainly due to the lack of professionalism of the doctor and aimless operation.That requires our vigilance.

5 ‘Spinal Fine Adjusting’ Manipulations Highlight the Importance of ‘Tendon Smoothing’

Shen Guo-quan summarizes the characteristics of Ding's tuina and proposes the concept of ‘spinal fine adjusting’ in response to the drawbacks of‘indistinguishable tendons and bones, inaccurate positioning, and difficult force control’ in conventional manipulations. We still take the left deviation of the spinous process of the axis as an example. The first step is to perform one-finger-pushing manipulation at the back of the occiput. The strength and frequency should be regulated according to different sensations under the fingers, with the tense part of the muscle being treated gently and slowly, and the weak part of the muscle being treated with greater force and quickly,which highlights the concept of ‘tendon smoothing’[17].After the tense muscles are relaxed and the loose muscles are stronger, the patient is placed in a left lateral position, and the operator holds the temporal region of the patient by the left hand and extends the sagittal axis gently. Then the head of the patient is passively flexed to the right by 15°. The operator suddenly expands the lateral flexion amplitude by 3-5°with a great force, and pushes forward and presses the transverse process of the axis by the right hand at the same time. Both hands coordinate the force, and a slight sliding sensation under the operator's hand indicates successful resetting. This manipulation is extremely low-risk and has better efficacy than conventional manipulations[26-27]. Unlike other ‘bone setting’ manipulations that emphasize steady, accurate,and fast explosive force, the ‘spinal fine adjusting’manipulation uses a gentle and controlled force. It is easy to see that the key to the success of this manipulation lies in the reasonable combination of the‘tendon smoothing’, which corrects the endogenous‘tendon-bone imbalance’ of the AAJ by balancing the exogenous stresses. The ‘tendon-bone balance’ is then restored by taking advantage of the situation. It is very difficult to successfully reset the spine without a reasonable ‘tendon smoothing’ manipulation. It can be said that ‘spinal fine adjusting’ is an extension of the‘tendon smoothing’ manipulation, and the level of the operator's ‘tendon smoothing’ manipulation largely determines the effectiveness of the technique, which places higher demands on tuina practitioners.

6 Rational Use of ‘Tendon Smoothing’ and‘Bone Resetting’ Manipulations Based on the‘Tendon-bone Balance’ Theory

According to the theory of ‘tendon-bone balance’,tuina manipulation should be rationally selected based on the primary and secondary order of ‘tendon’ and‘bone’ in the treatment of adult AAS. For AAS caused by strain, ‘tendon off-position’ leads to ‘joint subluxation’,so treatment should be based on ‘tendon smoothing’manipulations, supplemented by ‘bone resetting’.Injury-induced AAS is a case of ‘joint subluxation’leading to ‘tendon off-position’, and treatment should be based on ‘bone resetting’ manipulations,supplemented by ‘tendon smoothing’[7]. Most adult AAS patients have no obvious history of trauma, and most of the situations are ‘tendon off-position’ leading to ‘joint subluxation’. Cheng YB,et al[28]summarizes a variety of degenerative spinal disorders and proposes that ‘tendons and bones should be treated together,and tendon smoothing should take precedence’, which also supported the priority of ‘tendon smoothing’.However, ‘bone resetting’ should not be ignored when doing ‘tendon smoothing’ manipulations, and if the‘bone resetting’ manipulations can be reasonably chosen to assist, the therapeutic effect of ‘tendon smoothing’ can be more lasting. On the contrary, for some patients with ‘tendon off-position’ due to ‘joint subluxation’, the dominant position of ‘bone resetting’manipulations should be reflected, supplemented by the ‘tendon smoothing’ manipulations featured in the‘spinal fine adjusting’ manipulations. That can also make the effect of ‘bone resetting’ more significant.

7 Summary

The ‘tendon-bone balance’ of the AAJ is essential to maintaining normal joint function. When ‘tendon-bone imbalance’ of the AAJ is triggered by strain or injury, it may lead to AAS and cause a series of clinical symptoms. The majority of adult AAS patients are suitable for tuina treatment, but the conventional manipulations do not pay attention to ‘tendon smoothing’ and the safety and effectiveness of ‘bone resetting’ are also unsatisfactory. Also, it lacks‘tendon-bone balance’ theoretical guidance. When treating adult AAS, we should first identify the order of‘tendon off-position’ and ‘joint subluxation’, and reasonably use ‘tendon smoothing’ and ‘bone resetting’manipulations. The ‘spinal fine adjusting’ manipulations are featured by ‘tendon smoothing’ techniques, and various modified ‘bone resetting’ manipulations are safe and effective. Tuina practitioners should integrate and complement the strengths and weaknesses of multiple schools, they can go further in the treatment of adults with AAS.

Conflict of Interest

There was no potential conflict of interest in this article.

Acknowledgments

This work was supported by Pilot Project of Clinical Cooperation between Chinese and Western Medicine for Major Difficult Diseases [国家重大疑难疾病中西医临床协作试点建设项目, No. ZY(2018-2020)-FWTX-2005];Scientific Research Program of Shanghai Science and Technology Commission (上海市科学技术委员会科研计划项目, No. 16401970200); General Project of National Natural Science Foundation of China (国家自然科学基金面上项目, No. 81373763).

Received: 29 October 2020/Accepted: 19 December 2020