Directional preference research:

Wernecke et al. (2011) define directional preference as either (1) a specific direction of trunk movement or posture observed during the physical examination or (2) a specific aggravating or easing factor reported by the patient during the subjective history that alleviates or decreases the patient’s pain, with or without the pain moving or increasing the patient’s lumbar ROM. It is possible for patients to have a directional preference but not meet the definition of centralization, which is characterised by spinal pain and referred spinal symptoms that are progressively eliminated in a distal-to-proximal direction in response to therapeutic movement and positioning strategies. When a patient has a directional preference with centralization vs. a directional preference without centralization or no directional preference at all, the prognosis of patients treated with a directional preference management therapy method improves.

Donelson et al. (1991) randomly assigned 145 patients to two distinct procedures to study the impact of flexion and extension on symptoms in the short term. In one group, flexion movements were performed first, followed by extension movements, standing first, then lying second; in the other group, the order of movements was reversed. Whatever protocol was used, flexion had the impact of increasing symptoms, and extension had the effect of lowering symptoms. Individually, fourteen people reported less back discomfort. Thirty-one people were tested during flexion, and thirty-one subjects were tested during extension. Individually, eleven respondents experienced less distal limb discomfort during flexion, and fifty-six subjects experienced less pain during extension. Surprisingly, just one patient improved with both flexion and extension movements. An analysis model that expected various reactions to flexion and extension in central and peripheral pain and centralization\peripheralization was evaluated, and substantial changes in pain behaviour to the different movements were discovered.

Williams et al. (1991) studied the effects of two sitting postures on back and referred pain over a 24- to 48-hour period. A total of 210 individuals with acute and chronic complaints were randomly assigned to a kyphotic or lordotic sitting group. Patients’ responses to various sitting postures were examined while they were in the clinic, and they were then told to take a specific position while they sat for the next day or two. The lordotic group was given a lumbar roll and told to keep their lordosis; the kyphotic group was given a portable cushion and told to sit with their spine in flexion. On returning to the clinic, the back and referral symptoms were evaluated once more. In the lordotic group, there was a significant reduction in back and leg discomfort at all test points compared to baseline, but no change in the kyphotic group. While there was no significant difference between the two groups at baseline, they did differ considerably in terms of back and leg pain following the intervention. The lordotic group experienced a 21% and 56% reduction in back and leg pain intensity, respectively, whereas the kyphotic group experienced a 14% rise in back pain intensity and no change in leg pain intensity. In 6% of the lordotic group and 24% of the kyphotic group, pain spread below the knee. In contrast, 56% of the lordotic group and 10% of the kyphotic group experienced soreness above the knee.

Snook et al. (1998) investigated the effect of reducing early morning flexion in a group of individuals with chronic back pain who had been experiencing symptoms for an average of seventeen years. After six months of monitoring symptoms, patients were randomly assigned to either the intervention or a control group that conducted flexion exercises, which a previous study found to be useless. The intervention group was given instructions and assistance in following a tight regimen of abstaining from flexion for the first two hours after rising, followed by a relative restriction on flexion activities. The control group received the intervention after six months. At six months, the intervention group had significant improvements in pain intensity, days in pain, and medication use that the control group did not have. There were further improvements in pain for the intervention group after one year, as well as a number of significant changes in both groups relative to pain and impairment compared to baseline. This trial had a significant drop-out rate, particularly in the intervention group, with a 30% attrition rate after randomization. This may be a witness to the difficulties of implementing such behavioural adjustments; the patients’ posture guidelines were quite rigid and demanding. Snook (2000) reports that 53 of the sixty patients who completed the trial were followed up on three years later. Sixty-two percent of this group said that the intervention was still useful and that it was restraining their flexion, and 74% reported a further reduction in days in pain.

Long and Donelson (2004) found that exercise prescription based on directional preference produced better results than comparison groups that completed activities in the opposite direction of the indicated directional preference. Because diverse mechanical back pain problems exhibit varied directional preferences, all back pain cannot be treated as a homogeneous entity, nor can it be assumed that all patients will respond similarly to the same activities.

A systematic review of RCTs that used a directional preference management approach for LBP identified five high-quality RCTs that demonstrated moderate evidence that directional preference management was more effective than a number of comparison treatments for pain, function, and work participation at short- and intermediate-term follow-ups when directional preference management was applied to patients with LBP who demonstrated a directional preference.

Several studies have compared a directional preference management programme to other physical therapy interventions for patients with subacute or chronic low back pain, such as spinal stabilisation exercises (Miller ER, et al. 2005), spinal manipulation (Paatelma M, et al. 2008; Peterson T, et al. 2011; Schenk R, et al. 2012), or neurodynamic exercises (Sousa Filho LF, et al. 2022). They discovered improvements in pain and function in both groups, but no statistically significant difference between the two groups.

Centralisation studies

for

prognostic and diagnostic utility:

Donelson et al. (1990) were the first to describe the phenomenon in the literature. This study comprised 87 patients with pain radiating to the buttock, thigh, or calf out of 225 consecutive patients with back pain. Patients had a variety of acute and chronic symptoms. Mechanical evaluation and treatment were performed utilising endrange repeated sagittal and frontal plane movements that eliminated distal discomfort. Outcomes were deemed outstanding if there was complete relief of symptoms and good if there was partial relief and improvement in three secondary criteria: patient satisfaction, physical examination improvement, and return to work. A fair outcome was defined as partial relief with failure to progress in some secondary criteria, whereas a poor outcome was characterised as no relief. Centralization occurred primarily on the initial visit and occasionally in the days that followed. The opposite movement to that that centralised symptoms was usually intensified. Seventy-six percent (87%) of patients supported centralization, and seventy-two percent (83%) reported good or outstanding outcomes. Centralization of symptoms happened in 100% and 77% of individuals who had an excellent or good outcome, respectively, while it happened in 57% and 37% of those who had a fair or poor outcome. Centralization occurred independent of the length of time symptoms had been present: 89% in those with fewer than four weeks of symptoms, 87% in those with four to twelve weeks of symptoms, and 84% in those with more than twelve weeks of symptoms.

Long (1995) investigated centralization in a group suffering from persistent low back pain. 233 patients were classified as centrahsers or non-centralizers based on their reaction to an initial mechanical test; the most distal, but not all, lower limb symptoms had to be eliminated. Patients were subsequently placed in a work-hardening programme, following which outcome data was collected by staff who were not aware of the classification. Both groups reported significant reductions in pain intensity measures, whereas centralizers reported better improvement as well as a higher rate of return to work (68% vs. 52%). Lifting ability and Oswestry disability ratings improved significantly, although there were no differences between groups.

Karas et al. (1997) examined the prognostic value of centralization and Waddell’s non-organic indicators for return to work in a back pain population that was out of work. A total of 171 patients were investigated, with 126 of them being used in the final calculations. Within two treatments, centralization was defined as proximal movement or a reduction in symptoms in response to movements in one direction. Treatment included workouts in the patients’ preferred direction, function rehabilitation, and physical fitness. Low Waddell scores and centralization were both related to increased rates of return to work. High Waddell scores and failure to centralise or eliminate symptoms quickly are both related to a lack of responsiveness to mechanical therapy and anticipate a poor prognosis.

Sufka et al. (1998) compared patients who totally centralised symptoms within two weeks versus those who did not. Those with chronic symptoms had poorer outcomes. Centralization was more common in those with acute symptoms compared to those with chronic symptoms (83% vs. 60%) and in those with back pain solely compared to those with pain below the knee (80% vs. 43%). Functional outcome indicators improved more in the centralization group.

Donelson et al. (1997) performed a one-time mechanical evaluation on 63 chronic back patients and compared their findings to those of diagnostic disc injections. Patients were categorised as centralizers, peripheralizers, or no change after the mechanical examination. Following discography, positive discogenic pain and annulus competency were classified. The investigator conducting the discogram investigations was not aware of the mechanical assessment results. 74% and 69% of individuals with central or peripheral pain reported positive discogenic pain, respectively, compared to 12% in the no-change group. A competent annulus was found in 91% of those who centralised and 54% of those who peripheralized.

Werneke et al. (1999) studied 289 patients with acute back and neck pain. Patients were divided into three groups based on their centralization, non-centralization, and partial reduction. Centralization was defined considerably more firmly than in prior research as the permanent elimination of pain from the initial evaluation, with additional proximal movements of discomfort on all subsequent visits until all pain is eliminated. The partial reduction group allowed for a more gradual reduction in distal discomfort over time and between clinic sessions. Centralization occurred less frequently (31%) with this stricter criterion than in other research, but partial reduction occurred frequently (44%). The whole centralization group had fewer visits on average than the other two groups, four versus eight. However, in terms of pain and function results, both the centralization and partial reduction groups outperformed the non-centralization group. As a result, partial centralization took longer but accomplished the same result; this occurred in two unique patterns. A third had a proximal shift in pain on the first visit that was maintained, while 71% had no change on the first visit but gradually centralised over time. By the third appointment, around half had shown this improvement, 74% by the fifth visit, and 93% by the seventh visit. The authors suggest that the improvements in this group were attributable to the natural history of acute difficulties, but they might also have been the effect of the prescribed exercise therapy if patients had not shown an improvement by the seventh appointment, when no significant changes were noticed.

Werneke and Hart (2001) investigated the ability of centralization versus non-centralization to predict outcomes one year after patients were enrolled in the prior study (Werneke et al., 1999) in 223 patients with back pain; 84% were contacted. The centralization and partial reduction groups were compared to the non-centralization group. Other demographic, historical, occupational, and psychosocial aspects were also taken into account. Pain severity, length of symptoms, prior spinal pain, workers’ compensation, work satisfaction, Waddell’s non-organic indicators, depressive symptoms, somatization, and fear-avoidance were among the characteristics identified as having significant predictive significance. Pain severity, return to work, sick leave, function at home, and health care utilisation were all factors examined. At one year, nine of the twenty-three independent factors exhibited an individual predictive influence on certain outcomes. However, only two factors remained significant in a multivariate logistic regression analysis that included all of the important factors from the univariate studies. Only the categorization of centralization or non-centralization and leg pain were initially predictive, with pain pattern classification predicting four of the five outcomes. Centralization appears to identify a subset of spinal patients who will respond well to conservative treatment (Aina A. et al. 2004).

Skytte (2001) evaluated sixty patients divided into centralizers (25) and non-centralizers (35) and observed them for a year. Surgery was performed on 46% of the non-centralization group and 12% of the centralization group. Significant differences in reported disability and leg pain favoured the centralization group, but no differences in medication use, sick leave, or back pain were observed.

Laslett M. et al. (2005) evaluated 107 patients who had clinical examinations, discography at two or more levels, and computed tomography after discography. Thirty-eight people were unable to withstand a comprehensive physical examination and were therefore eliminated from the main study. Distress was widespread, as were disability and pain intensity assessments. Sensitivity, specificity, and positive probability ratios for pain distribution and intensity changes observed during repeated movement testing were 40%, 94%, and 6.9, respectively. Sensitivity, specificity, and positive probability ratios were 46%, 80%, and 3.2 in the presence of severe impairment, and 45%, 89%, and 4.1 in the presence of distress. Sensitivity and specificity were 37% and 100% in the subgroups with moderate, mild, or no handicap, and 35% and 100% in the subgroups with little or minimal distress. The authors came to the conclusion that, whereas centralization is highly specific to positive discographies, it is diminished in the context of severe handicap or mental distress.

McKenzie Method of Mechanical Diagnosis and Therapy (MDT) association with Psychosocial Factors

Numerous studies, including one systematic review, have looked into the relationship between MDT and psychosocial outcomes. There is a link between fear avoidance beliefs, somatization, depressive symptoms, and pain self-efficacy.

Werneke (2018): This cohort study included 138 patients with LBP and a significant STarT risk. Those with a direction preference (DP) who received a matching intervention had significant and clinically meaningful differences in function as compared to those without a DP.

Werneke (2020): This large cohort study tracked 705 patients who got MDT and completed functional scores and the STarT Back Questionnaire at baseline. Over 90% of those classified as high-risk were reduced to low (67%) or medium risk (25%), demonstrating that MDT care may minimise some of the STarT physical and psychosocial deficits.

Kuhnow (2020) discovered a link between MDT and improvements in fear avoidance, pain self-efficacy, depression, and psychological distress.

MDT helps in avoiding potential surgery and cost-saving implications

Several studies have demonstrated the potential of MDT for pre-surgical screening and intervention to lower spine surgery rates. This could result in huge cost savings.

In the Rasmussen (2005) study, lumbar disc surgery rates were reduced by 50% four years after the installation of MDT-based spine clinics in a Danish county.

Transforaminal epidural injections followed by MDT indicated the potential to be a beneficial therapy in averting surgical treatments for individuals with lumbar disc herniation in the Van Helvoirt (2014) research.

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