Clinical Assessment

Fig. 4.1

In this sesamoid axial view , the crista is shown to be laterally rotated, indicating that the first metatarsal is externally rotated

While radiographic examination can show deviation of the first ray in these different planes, flexibility, reducibility and joint adaptation cannot be assessed effectively without a thorough clinical examination. Evaluating these parameters are important when selecting a surgical procedure that effectively reduces the deformity and maintains the correction. Reducibility of a medially deviated first metatarsal can be relatively easily assessed in a clinical examination. When a first intermetatarsal angle is manually reducible in a clinical examination, surgical correction of the deformity may be achievable without proximal osteotomy or arthrodesis. For example, soft tissue balancing, tethering or distal metatarsal osteotomy techniques may adequately reduce the overall deformity by negating the retrograding buckling force caused by the long extensor and flexor (Fig. 4.2). Conversely, a proximal osseous procedure may be necessary in those non-reducible deformities. For example, first metatarsophalangeal joint (MTPJ) arthrodesis for correction of HV would not improve the intermetatarsal (IM) angle unless the first ray is passively reducible in a preoperative clinical examination. Without a reducible intermetatarsal space, a significant gap between the hallux and the second digit may occur after correcting the hallux position on the metatarsal with this procedure.

Fig. 4.2

These flexible deformities were corrected successfully without proximal osseous procedures. (a) Distal metatarsal osteotomy, (b) tethering bunionectomy and (c) first metatarsophalangeal joint arthrodesis reduced intermetatarsal and hallux valgus angles

On the other hand, excessive motion of the first ray can be problematic and warrants an extra attention. While most of the bunion deformities have some degree of first ray instability, magnitude of hyperflexibility should be assessed. This needs to be evaluated with a clinical examination since radiographic examination in this matter can be inaccurate [4, 5]. In order to assess the magnitude of mobility in the first ray, one can simply squeeze the forefoot from the medial to lateral direction (Fig. 4.3). Alternatively, one can squeeze the forefoot while the other hand stabilizes the second metatarsal to isolate the first IM space (Fig. 4.4). Also, it is beneficial to observe the location and angulation of the hallux while performing this squeeze test. It is important to note whether the hallux further deviates laterally or positions back to its original position. If it further abducts with lateralization of the first metatarsal, significant contracture of the lateral MTPJ can be present. Lateralization of the first metatarsal otherwise should place the long flexor and extensor over the first ray axis and help realign the hallux onto the first metatarsal head. The squeeze test can also be done simultaneously with reduction of the hallux at the MTPJ, as it negates the retrograde buckling force and may further reduce the IM angle. For more accurate assessment, this can be done under fluoroscopy if available (Fig. 4.5). Reducibility of the sesamoids can also be observed at the same time. Pain associated with these maneuvers should also be noted. A painful, forced reduction may result in a poor post-operative outcome if the area of pain is not addressed adequately. For example, HV correction with first MTPJ arthrodesis can result in painful the tarsometatarsal joint (TMTJ) or base of the first IM space post-operatively if the deformity had a non-reducible IM angle.

Fig. 4.3

The first ray is manually and passively reduced. A reducible first ray will result in a narrower forefoot

Fig. 4.4

To prevent from other interspaces contributing in the narrowing of the forefoot, one can stabilize the second metatarsal while performing the squeeze test

Fig. 4.5

A manual, passive reduction of the first ray is confirmed under fluoroscopy

In the frontal plane, reducibility can be assessed by internally rotating the hallux, which in turn, internally rotates the first metatarsal (Fig. 4.6) [6]. This can also be done with reduction of the IM and HV angles to simulate the actual surgical reduction. Again, this is more helpful with an aid of fluoroscopy if available. Reduction of the sesamoids, change in curvature of the medial and lateral first metatarsal shaft cortex are the indications of a mobile first ray in the frontal plane. In surgery, reduction of the first ray in the frontal plane can be achievable with different techniques that de-rotate the first metatarsal or reduce underlying deformities, such as pes planus or metatarsus adductus deformities.

Fig. 4.6

The hallux is internally rotated to assess the reducibility of the first metatarsal in the frontal plane

In the sagittal plane, excursion of the first ray relative to the lesser metatarsal should be evaluated. The excursion is often referred to as flexibility of the first ray. In a normal foot, the motion is mainly coming from the naviculocuneiform joint (NCJ) and minimal motion is coming from the TMTJ [7, 8] though more motion in the TMTJ is present in a foot with metatarsus primus varus (MPV) . An increased motion at the TMTJ comes in a pathological foot with ligamentous attenuation [9] and/or weakening of the dynamic stabilizers, such as the peroneus longus. When unstable, one should gain a sense of how much instability is clinically appreciated. An unstable first ray can result in metatarsus primus elevatus and hallux limitus [10, 11].

Elevation of the first ray is often examined with a lateral x-ray view. However, it is as important to assess the position of the first ray in the open kinetic chain clinically as well. Many of the elevated first rays, viewed in the weightbearing lateral x-ray, can be resulted from the ground reacting force applied to the first metatarsal head, that is otherwise plantarflexed in the open chain [12]. The falsely and radiographically elevated first ray in a forefoot valgus patient (the first ray is plantarflexed in the open kinetic chain) should not be further plantarflexed with surgery as it may cause sub-first metatarsal pain post-operatively. To assess the position of the first ray in the sagittal plane clinically, a patient’s calcaneus is placed in the examiner’s hand, in line with the long axis of the leg. The other hand is then used to grasp the fifth metatarsal head. The examiner’s thumb (on the hand cupping the calcaneus) is then placed over the talonavicular joint while the subtalar joint (STJ) is manipulated using the other hand until the head of the talus is covered by the navicular. At this point, the STJ is considered to be in a neutral position and the forefoot is observed in the frontal plane (Fig. 4.7). If the patient’s first ray is higher than the lesser metatarsals, it is considered elevatus or supinatus, and the examiner should be highly suspicious of unstable first ray and the ray may need to be surgically plantarflexed.

Fig. 4.7

Elevation of the first ray is evaluated with the subtalar joint in the neutral position

Anatomical structures that are responsible for stabilization of the first ray should also be examined. Dynamic stabilizers , such as long flexor and peroneus longus tendons can be evaluated by the regular muscular examination and with gait observation. Lack of re-supination, overly flexible or rigid medial column and inefficient propulsion are indicative of attenuation or loss of biomechanical advantage of one or more of the first ray dynamic stabilizers. Damages to static stabilizers, such as plantar and inter cuneiform ligaments may be associated with pain on palpation and/or range of motion in the corresponding areas.

In open kinetic chain examination, one of the most popular methods of evaluating the instability of the first ray was described by Root and Merton [13]. Hypermobility was referred to as a total (dorsiflexion and plantarflexion ) excursion of the first ray of more than 1 cm in the sagittal plane. Yet, no scientific rationale for this definition was originally provided. Reproducibility, accuracy, sensitivity and clinical significance of this examination is therefore uncertain. However, later studies conducted by other investigators, focusing mainly on identifying an average motion of the first ray between symptomatic bunions and a control without bunion deformity, showed a normal average range motion in the first ray to be similar to that of the range of motion described by Root and Merton [14–16].

Many advocate arthrodesis of the TMTJ for more hypermobile bunions, but some studies show good surgical outcomes with joint preservative procedures [5, 17]. Ambiguity of the definition of hypermobility however makes these findings difficult to interpret. Nevertheless, one can appreciate the difference in amount of excursion form a patient to patient using this evaluation technique. It has been shown that dorsiflexory resistance of the first ray is compromised when the first metatarsal, sesamoids and hallux are malaligned [18]; therefore, examination of the first ray instability also provides information on magnitude of the HV deformity. To perform this test, one can hold the first metatarsal with one hand while the other holds the lesser metatarsals. Having the ankle and subtalar joints in their neutral positions, the first ray is maximally dorsiflexed and plantar flexed (Fig. 4.8). The excursion in reference to the fingernails is recorded. Alternatively, to simulate a normal gait and to activate the windlass mechanism, the hallux is dorsiflexed before the first ray can be assessed for hypermobility [19, 20] (Fig. 4.9). Lack of stabilization with this maneuver indicates that his/her windlass mechanism may be already compromised and improvement of the first ray function after surgery may be challenging.

Fig. 4.8

Mobility of the first ray is examined in the sagittal plane while the lesser metatarsals are stabilized and the ankle and subtalar joints are placed in their neutral positions

Fig. 4.9

Dorsiflexion of the hallux mimics normal gait and activates windlass mechanism before mobility of the first ray is assessed

Generalized ligamentous laxity in a patient should be also examined. Ligamentous laxity results in instability of the first ray and may mean that it is more difficult to maintain the surgical correction. Namely, an instrument, such as Beighton Score , can be utilize to assess the degree of ligamentous laxity objectively by evaluating the metacarpophalangeal joints in the hands, hyperextension of the elbows and knees and forward flexion of the trunk [21] (Fig. 4.10).

Fig. 4.10

Generalized ligamentous laxity in a patient can be evaluated by examining other parts of the body

Other signs that may suggest instability of the first ray are found in the second ray. A patient may possess a sub-second metatarsal biomechanical hyperkeratotic lesion, plantar plate rupture/attenuation of the second MTPJ and hammer toe deformity (Fig. 4.11). A visual, dermatological examination to rule out the biomechanical lesion, a dorsal dislocation maneuver to stress the plantar plate to rule out the plantar plate pathology and thorough hammer toe evaluation are critical in a comprehensive bunion evaluation. It is also important to note that the relationship between the hallux and the second digit often changes with weightbearing. Crossover deformity, for example, can worsen with a loading of the forefoot (Fig. 4.12).

Fig. 4.11

A second submetatarsal lesion may indicate unstable first ray

Fig. 4.12

Relationship between the hallux and the second digit is best evaluated in a weightbearing position. A degree of deformity often worsens when the forefoot is loaded in this manner

First Metatarsophalangeal Joint

In the first MTPJ, reducibility, flexibility and degree of joint adaptation should be carefully assessed clinically in the similar manner to those of the first ray. Compared to the TMTJ and NCJ, the first MTPJ is far more complex due to more tendon attachments and presence of the sesamoid complex; therefore, understanding characteristics of hallux valgus deformity in association with these structures is imperative. The sesamoids rest in the grooves adjacent to the crista in a normal foot. In HV deformity, the sesamoids are deviated in the transverse plane when viewed in the dorsoplantar projection of a plane radiograph relative to the first metatarsal head [22, 23], while the relationship between the sesamoids and the second metatarsal remains consistent [24, 25]. These relationships suggest that the first metatarsal is the moving part that is dislocating from the sesamoids. Deviation and subluxation of the first metatarsal out of the sesamoids can then result in degenerative changes under the first metatarsal [26] and this should be noted preoperatively to avoid unexpected residual pain after surgery. However, radiographic medial deviation of the first metatarsal does not always result in dislocation of the sesamoids out of their proper articular surfaces [27]. They can many times remain in the corresponding grooves, yet they “appear” to be laterally deviated in the dorsoplantar x-ray view. This phenomenon is due to simultaneous external rotation of both the first metatarsal and the sesamoids as these structures remain congruous (Fig. 4.13). In a cohort of 166 HV feet studied by Kim et al., 26% of HV presented with a congruent sesamoid complex despite the apparent radiographic subluxation [3]. This explains that both lateral translation of the head of the first metatarsal and de-rotation of the first metatarsal have been reported to be efficacious is achieving reduction of the sesamoid position [25, 28–31] (Fig. 4.14).

Fig. 4.13

The sesamoids can either (a) sublux or (b) remain congruous as the first metatarsal medially deviates

Fig. 4.14

The sesamoid position was reduced with (a) lateral translation and (b) internal rotation of the first metatarsal

Range of motion examination at the first MTPJ in deformed and rectus positions of the hallux can provide information on the status of the sesamoid complex. When the first metatarsal is pronated but the sesamoid complex is congruous, a smooth, painless range of motion in the deformed position is not uncommon. On the other hand, subluxation of the sesamoids out of the corresponding grooves can result in a painful range of motion with or without manual reduction of the first MTPJ in the transverse plane. If available, live radiographic examination with fluoroscopy can provide the definitive answer to the relationship between the first metatarsal and the sesamoids throughout the range of motion (Fig. 4.15). During this test, reduction of the sesamoids in the dorsoplantar view and sesamoid axial view while the hallux is reduced in the transverse and frontal plane and also through the range of motion in deformed and corrected positions are evaluated. If an IM angle can be reduced manually at the same time, it can also assist in reduction of the sesamoid position. It should be noted that sesamoids may reduce into more congruous position with dorsiflexion of the hallux and the sesamoid axial view may underestimate the amount of subluxation [32]. Non-reducible sesamoids may warrant some type of osseous procedure. On the other hand, in a reducible deformity, when the range of motion is painful in the corrected position, surgical reduction of the deformity may result in an even more painful joint post-operatively. Therefore, these evaluations are important to determine what type of procedure is necessary not only to reduce the deformity but also to achieve a non-painful joint range of motion after surgery.

Fig. 4.15

A range of motion examination with live fluoroscopic guidance can show the relationship of the sesamoids with the first metatarsal and the dynamics of the sesamoid complex

The standard evaluation for hallux limitus should also be employed while assessing the range of motion. As many HV deformities are associated with first metatarsal elevation, a decreased dorsiflexion at the MTPJ is not uncommon. The prominence many times appears more dorsally in these situations with a limited dorsiflexion (Fig. 4.16). They may also present with hallux extensus from hallux interphalangeal joint (IPJ) compensation. These findings should be well documented and a patient should be informed about it preoperatively, as some patients do not notice the limited range of motion until after the corrective procedure. Again, this clinical examination is conducted with the hallux in deformed and corrected positions. The patient should also be informed about the potential loss of range of motion after surgery, especially when the range of motion worsens when the hallux is reduced in a rectus position during the clinical examination. The range of motion at the hallux IPJ is also assessed at the same time. A painful range of motion in the IPJ will most likely be problematic if the MTPJ range of motion decreases post-operatively.

Fig. 4.16

This pronated foot presents with a medial column collapse, unstable first ray and elevation of the first ray. This type of foot many times results in hallux limitus , evidenced by limited range of motion and more dorsally located prominence at the metatarsophalangeal joint

While assessing the range of motion, an amount of contracture of the lateral structures should also be assessed. A chronic HV deformity often results in contracture of the lateral capsule, adductor tendon and long flexor and extensor. Also, weakening of the antagonists, such as abductor hallucis, can be present [33] and should be noted. It has been shown that an older age and HV deformity are risk factors for reduction in size and change in morphology of the abductor hallucis muscle [34, 35]. As seen in other areas, such as the ankle joint, release of contracture, shortening of the segment and augmentation of insufficient structures may be necessary to reduce the chronic deformities. Contracture of these anatomical structures should also be assessed in weightbearing examination. Often, long extensor contracture is not appreciated until a patient bears weight. Bowstringing of the extensor tendon may be apparent only with weightbearing. Further, in many cases, lateral deviation of the hallux worsens with weightbearing. Lateral tracking of the hallux should be assessed in this position as well as in a slightly dorsiflexed position, as some intrinsic, extrinsic muscles and ligamentous structures become taut in this position. As mentioned earlier, relationship between the hallux with the second digit should also be observed in this position.

Crepitus associated with a range of motion of the MTPJ suggests arthritic changes. Often the joint can be without crepitus in a deformed position but it can present when the deformity is corrected manually into a rectus position as the joint is put through the range of motion. This suggests adaptation of the joint or a laterally deviated articular cartilage on the first metatarsal head. When the joint motion is smooth in the abductovalgus position, articular cartilage may no longer exist on the medial side. This is not always appreciated with radiographic examination.

Even without crepitus, pain felt with range of motion of the first MTPJ in different positions may suggest a chondral lesion of the articular surface as the prevalence of this condition is extremely high in HV [36–38]. This condition is often underestimated with radiographic examination; therefore, a careful clinical examination is critical [39]. It should be noted that the condition not only occurs in the anterior articular surface of the first metatarsal, but also frequently under the metatarsal head where it articulates with the sesamoids [36, 40]. Similarly, synovitis in the first metatarsophalangeal joint can be a cause of the patient’s main complaint in HV [41]. In these intra-articular conditions, a diagnostic intra-articular block can differentiate the pain in the joint from the pain coming from the medial prominence. The hallux is slightly dorsiflexed and the needle can be introduced in the dorsal capsular pouch, and a small amount of short-acting anesthetic agent can be injected in the joint.

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