Leg Length Inequality as a Cause of Functional Scoliosis in a Patient Following a Total Hip Replacement

Original Article

Nathan A. Hinkeldey, DC1, 2, William E. Morgan, DC, DAAPM3

1 Staff Chiropractor, VA Central Iowa Healthcare System, Des Moines, IA

2 Adjunct Faculty, Palmer College of Chiropractic

3President, Parker University

[email protected]

Published: September 2016

Journal of the Academy of Chiropractic Orthopedists

September 2016, Volume 13, Issue 1

This is an Open Access article which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The article copyright belongs to the author and the Academy of Chiropractic Orthopedists and is available at: http://www.dcorthoacademy.com. © 2016 Neff/Schielke and the Academy of Chiropractic Orthopedists.

ABSTRACT

Introduction: Leg Length Inequality (LLI) has been identified as a mechanism that can lead to scoliosis. LLI is a relatively common outcome of total hip replacement (THR) surgery; however, few studies illustrate the potential for THR to result in scoliosis. The current report discusses a scoliosis that may have resulted from LLI following a THR.

Clinical Features: A 65-year-old woman sought care at a hospital based chiropractic clinic for an acquired scoliosis following a THR surgery. This was not present in plain film imaging taken prior to her THR surgery. Post-surgical leg length analysis revealed a significant LLI and subsequently, the rapid progression of a scoliosis.

Interventions and Outcomes: Post THR surgery radiographs of the hips illustrated significant asymmetrical leg lengths and progressing scoliosis.

Conclusion: A significant number of patients develop LLI following THR surgery. Non-surgical LLI have been found to cause or contribute to scoliosis; this case identifies a potential link between an iatrogenic LLI and the onset of scoliosis. The presenting case illustrates a patient that may present with back pain to the general chiropractic office.

Introduction

Acquired scoliosis following total hip replacement (THR) surgery is not well documented within the literature. Our paper describes a mature patient who presented post-THR who subsequently developed a 40-degree scoliosis. Total hip replacement surgery is an effective intervention for reducing hip dysfunction and decreasing pain; however, a substantial number of patients report poor outcomes related to Leg Length Inequality (LLI), nerve palsies, low back pain, and gait abnormalities (1, 2). Over 70% of post-THR patients are left with some LLI (3), and 23-56% of THR surgeries result in LLI of greater than 1 cm (4, 5, 6); subsequently, the Joint Commission has listed LLI as one of the 19 major events deserving additional focus and attention in healthcare safety (7). A search was conducted through Pubmed, Google Scholar, and 17 other databases within OVID using the terms leg length inequality, scoliosis, iatrogenic scoliosis, total hip replacement, and total hip arthroplasty. Scoliosis is defined as a lateral spinal deformity in a skeletally mature adult with a Cobb angle greater than 10 degrees. There are four type of scoliosis. Type 1 is termed primary degenerative scoliosis and is a result of disc degeneration and/or facet joint arthritis. Type 2 is known as idiopathic adolescent scoliosis, which progresses into adult life. Type 3a is termed functional scoliosis and results from pelvic obliquity due to LLI, hip pathology, or as secondary curves. Type 3b is development of the lateral curvature as a result of metabolic pathology (8).

Functional scoliosis is related to LLI (8), but only one article has illustrated a possible connection between THR and progression of lateral spinal curvature. Moreno et al evaluated the effects of leg length discrepancy following THR using a 3D motion capture system in standing subjects and found a 1 cm difference caused significant alterations in posture and gait. They also noted that limb length inequality can result in pelvic obliquity, asymmetric loading patterns, and progressive dysfunction; therefore, the intent of their study was to analyze the effects of heel lifts on LLI. Group I was fitted with a heel lift equal to the LLI, group II was fitted with a heel lift not equal to LLI, and group III was not fitted with a heel lift. After 3 months, the groups were re-evaluated. Group III had progressive pelvic obliquity, more back pain, and noted spinal deformity, while group II had some who improved and others whose obliquity and spinal deformity increased. Group I had full resolution of the symptoms and a stable pelvic posture as defined by this study’s authors (9). Leg length inequality can lead to scoliosis (8), and total hip replacement surgery can create leg length inequality (1, 2). However, little information is available regarding LLI secondary to THR and resulting in scoliosis. There are those who believe that LLI post-THR does not result in pain or alteration in gait(10); however, in addition to Moreno et all (8), Betsch et al illustrated that LLI greater than 20mm resulted in significant biomechanical alterations related to pelvic rotation and lateral deviation (11). Others have noted that LLI less than 2 mm is a static disorder and correction of the LLI will eliminate the scoliosis (12). We identified a patient who, after undergoing a THR, developed a LLI of 27mm and subsequent scoliosis of 40 degrees over 4 years.

Case Report

A 65-year old female patient presented initially to the hospital-based chiropractic clinic on 4/18/2008 with a mild backache for one visit before having a left THR on 4/29/2008. Plain film radiographs illustrated severe degenerative joint disease in the left hip that had resulted in prolonged pain and dysfunction. Her personal history was negative for inflammatory arthropathies, obesity, surgeries, or other systemic diseases; however, lumbar spine osteopenia was noted from a bone density examination. Following the surgery, the patient’s back pain increased. During a post-operative follow-up visit on 9/19/2008 with the orthopedic surgeon, a CT scanogram was taken and revealed a LLI of 27mm (figure 1).

Figure 1

Figure 1

A lumbar spine radiograph was also taken on this date and revealed a 15 degree dextroscoliosis using a Cobb angle (figure 2).

Figure 2

Figure 2

The patient did have a previous lumbar spine radiograph dated 3/10/2005, which was used for comparison, and that radiograph illustrated no significant lateral curvature (figure 3).

Figure 3

Figure 3

The patient returned to the hospital based chiropractic clinic for two additional visits on 11/21/2008 and 12/10/2008 with subjective complaints of severe low back pain. The patient’s treatment plan consisted of continuous passive motion using a flexion distraction table with light posterior-anterior joint manipulation in addition to instruction for core bracing. The patient’s pain persisted, prompting the writer to obtain a right hip radiograph which revealed degenerative joint disease. The combination of degeneration and LLI resulted in the patient and the orthopedic surgeon choosing to proceed with a right THR on 7/17/2009. Three months following the right hip replacement, another lumbar radiograph was taken that demonstrated a progression of her scoliosis to 33 degrees (figure 4). The extent of the rotatory progression was especially noteworthy. Symptoms persisted and a scoliogram was performed on 1/29/2010 and revealed progression of the lateral curvature to 35 degrees.

Figure 4

Figure 4

On 2/24/2010, the patient returned to the hospital-based chiropractic clinic with pain rated 3/10 on an 11-point scale that began 18 months prior, at the time the initial lumbar spine radiograph was taken (figure 2). The pain was rated as high as 5/10 within the last 24 hours, and 8/10 within the last 30 days. Subjectively, standing was listed as provocative while massage therapy and physical therapy provided some degree of relief She also noted a large “hump” on her back that she hadn’t noticed prior to the either THR. She was seen at a frequency of 2 visits per week for 10 weeks with treatment consisting of core stability exercises, lateral bend stretching over a bolster, continuous passive motion flexion distraction with light posterior to anterior prone spinal manipulation. The patient was also fitted with a 9 mm heel lift on the right. The size of the heel lift was chosen because it was the largest lift that the clinic had, it reduced the LLI to under 20 mm, and the patient reported relief with this lift when trialed in clinic. Following the third appointment, the patient reported pain severity at 1/10 which persisted until discharge on 7/23/2010. The proposed frequency was 3 visits per week; however, the patient lived four hours away and preferred to coordinate her appointments with semi-weekly family visits. Regular exercise like walking was suggested and neurosurgery was consulted due to the severity of the curvature. Neurosurgery suggested multisegmental spinal fusion as an option to correct the scoliosis; however, the patient chose to forgo the suggested intervention at that time. On 8/30/2012, another scoliogram was performed and revealed a 40-degree curvature with right lateral subluxation of L1 relative to L2 (figure 5).

Figure 5

Figure 5

The continued pain prompted a right THR revision on 9/24/2012. Pain, altered spinal contours (figure 6),

Figure 6

Figure 6

and altered gait persisted post-revision. To date, her symptoms and imaging have progressed. She has continued to be followed by neurosurgery and has remained undecided regarding multisegmental spinal stabilization. A timeline has been included as a summary for the points above (Figure 7).

Figure 7

Figure 7

Discussion

The report presents a compelling link between an iatrogenic leg length discrepancy and the onset of scoliosis in an otherwise mature spine. LLI is common amongst the THR population. Following placement of the implant, if the surgeon feels that the implant is too loose, a larger implant will be placed to prevent dislocation, which adds length to that lower extremity (1). While no literature exists to date correlating post-THR LLI to scoliosis, the European Spine Journal released a review of adult scoliosis, which identified LLI and pelvic obliquity as one of the 4 major possible causes of scoliosis (8). In addition, Giles et al have provided evidence that LLI and pelvic torsion result in asymmetry of lumbosacral facet joint angles, postural scoliosis, concavities in the vertebral body end-plates, wedging of the fifth lumbar vertebra, and traction spurs (13,14). One reason this correlation may not be apparent in the literature is the inherent difficulty in quantifying LLI. Full spine standing A-P radiographs are commonly used to initially assess LLI; however, the CT scanogram is the most reliable and accurate technique because of its ability to take into account soft tissue contractures (15). If physicians suspect that their patient has a LLI, especially post-surgically, the CT scanogram would be the most appropriate method for quantification. Historically, most of the studies examining this topic were performed before the CT scanogram was identified as the method of choice for evaluating LLI; therefore, the amount of LLI may be over or underestimated. Within the timeline, the patient had only reported to the chiropractic clinic for one visit prior to the initial lumbar radiograph and lateral curvature measurement of 15-degrees. In addition, the patient was only seen two more times before another radiograph illustrated a 35-degree lateral curvature. The lateral curvature is much more likely to have been a result of LLI (8) or degenerative changes (8) as there is no evidence to suggest that manipulation is a cause of scoliosis. As for other treatments, the progression was rapid and earlier post-surgical follow up with the orthopedist may have resulted in prompter recognition of the LLI. Early recognition could have resulted in early intervention including corrective orthoses. It is worth noting that the literature does support initial treatment with a heel lift half of the size of the measured LLI (16). It is possible that the combination of early detection and correction may have slowed progression of the scoliosis.

Our case demonstrates a relationship between LLI following THR surgery and progression of scoliosis using acceptable standards of measurement (11, 13). We acknowledge that causes other than surgery may explain this particular acquired scoliosis. It is our opinion that the pain and dysfunction of degenerative hips, psoas inhibition or hypertonicity, unrecognized organic disease, or several other causes could potentially cause or contribute to this condition. It should be noted that the limitations related to this case include a lack of scoliogram or lumbar radiograph immediately prior to the initial THR, so it is unclear whether the LLI existed and, if so, to what degree, prior to the THR.

Conclusion

Leg length inequality can contribute to scoliosis (8) and total hip replacement frequently results in leg length inequality (1). It is our opinion that this case demonstrates the potential for hip replacement surgery to inadvertently cause or worsen a functional scoliosis. This case contributes to the body of evidence regarding post-surgical structural changes and is directed toward healthcare professionals who may treat musculoskeletal spinal disorders post-THR.

Funding Source and Potential Conflicts of Interest: No funding sources or conflicts of interest were reported for this case report.

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