A huge increase in the older population brings an anticipated increase in the prevalence of acute and chronic back pain and a challenge in the assessment of back pain in outpatient settings. In textbooks or guidelines, the location of back pain indicates the spinal disorder level, and palpation or percussion at the level of the spinal disorder yields pain, such conception is deeply embedded in minds of physicians, gradually forming a cognitive bias. In our prior study about back pain from OVFs, the patient-reported back pain location did not match the VF level, and the location from physical examination findings was not colocalized with the VF segment [13]. This study also showed that the incident RP, SPT, or ASPP was not clinically correlated with clinical parameters, and a false correlation existed between the clinical parameters and timing for seeking medical aid.
In the present study, we observed that back pain from OVFs results in disability or difficulty to lie supine or sit up from a supine position, such pain is elicited and refractory once the stress or loading on the axial spine changes and will improve (even disappear) while the trunk is static. Controlling the scope of activities and the amplitude of movements are approaches to escape back pain onset or refractory, which actually are pain behaviors. Marc Chmielnicki et al. [21] also reported typical symptoms from OVFs as spinal loading-dependent pain and a general restriction of physical mobility. Thus, OVFs may be defined as secondary osteoporosis vertebral lesions characterized by dynamic back pain and backache avoidance behaviors, leading to disability, limited lifespan, poor quality of life, and increased morbidity and mortality. In the study by Tae-Hoon Doo et al. [22], back pain from OVFs were classified into three patterns with elucidating the three discrepant pain mechanisms. Such mechanisms also supported our rationale of dynamic back pain and backache avoidance behaviors.
In this cohort, 53.6% of VFs were spontaneous, which was in accordance with that (46%) in a previous study by Patel et al. [11]. They also pointed out that the RP to the flanks and anteriorly was common (66%), and lying flat or the sitting position can improve the pain intensity, which is consistent with those observed in our study. However, they analyzed a small sample size of 30 patients and did not reveal the common clinical appearance. A heterogeneous proportion of different fracture types existed from that reported by Tae-Hoon Doo et al. [22]. The discrepancy in the sample size can be responsible for this. Additionally, regardless of the pain patterns and time courses, we outlined the common clinical presentation of OVFs. Paul F. Heini [14] subdivided OVFs into 4 classifications and underlined their clinical presentation: (a) acute and subacute single-level fractures with sharp localized mechanical back pain; (b) fractures with persistent instability appear with a characteristic symptomatology—an intense local pain sufficiently relieved once upright or lying supine; (c) (multiple) fractures with progressive/creeping vertebral collapse and loss of sagittal balance and posture have a diffuse backache and strain over the whole back; and (d) vertebral fractures with subsequent spinal stenosis/neural compression are concurrent with severe local mechanical back pain together with an RP that usually subsides in the supine position. They pointed out that an individual therapeutic option could be proposed based on this classified system. We supported the opinions that an establishment of the therapeutic decision-making of OVFs must be based on their heterogeneous clinical appearance, but the clinical presentations reported by Paul F. Heini cannot sufficiently guide the classification of this cohort of OVFs. Thus, the clinical application of the classification system is in question.
Back pain from OVFs has a heterogeneous clinical presentation that is commonly correlated with pain generators, such as VF, nerve tension, facet, postural muscle, and ligaments [10]. In the present study, patients with a BMD T-score ranging from − 2.5 to -3.5 or VF region located in T1–T9 had a statistically high possibility of incident RP, SPT, or ASPP, but these clinical parameters could not be clinically applicable to characterize patients with incident RP, SPT, or ASPP. The mechanism of RP may be one or more combinations of compression, inflammation, or microinstability to a spinal nerve root and/or dorsal root ganglion [10]. Such pain will improve while the patient lays supine. Likewise, the possible mechanism of ASPP is local stimulation of a spinal nerve root and/or dorsal root ganglion due to an instantaneous increased loading of the axial spine. Patel et al. [11], Heini [14], and Kendler et al. [23] elucidated a similar possible pain generation mechanism. Notably, the performance of the SPT and ASPP mechanical responses are warranted to explain the SPT- and ASPP-elicited pain.
Megale and colleagues [24] reported that the most common reason for driving medical care seeking behavior is surprisingly not back pain (48%) but an experience of trauma or injury (6%), a past diagnosis of fracture (6%), or a complaint of not being able to sleep. Emotionally, patients with a history of VF or VA may seek medical care once back pain is recurrent, but no correlation was found between the timing for seeking medical aid and history of VF or VA in this cohort of patients. We also found that patients with OVFs with a negative spinal deformity or one single VF seem to seek medical attention within 8 weeks of the onset of back pain. However, a reasonable explanation between the timing for seeking medical aid and clinical parameters cannot be elucidated clinically. The number of VFs cannot be predicted based on the timing for medical aid, because one single VF is prevalent. Moreover, a false correlation existed between the timing for seeking medical aid and the precipitating event. We speculated that education level, emotion, awareness of OVF, and socioeconomic factors may be considered to analyze the discrepancy of the timing for seeking medical aid. For this cohort of patients, although patients with one or two VFs had a higher statistical possibility to seek medical care within 8 weeks, no clinical significance existed because such a significant difference may result from a different prevalence of number of VFs [16, 25].
Study limitations
Our study had some limitations. First, our study has limitations in interpreting all results of the incident RP, SPT, and ASPP, because their mechanisms are not fully explained. However, we believed that a mechanical response focused on spinal palpation and percussion might be useful as an initial guide to hypothesize the possible mechanism of palpation and percussion-elicited pain and even expound the incident SPT or ASPP. Secondary, possible additional discrimination variables are lacking due to concomitant symptoms not being evaluated in the present study. Third, we did not collect data on educational level, acknowledgement of back pain or OVFs, or awareness of seeking medical aid, so the reason why patients with OVFs did not seek medical attention at the point of back pain onset was not fully interpreted. Fourth, a few patients with OVFs with RP to the leg were not enrolled due to the prior prospective study design [13].