In this retrospective study, we followed up 153 patients who were diagnosed with both hip joint disease and lumbar degenerative disease before surgery. They all received THA. These operations were performed by 3 experienced joint surgeons. Through our follow-up, it was found that the symptoms of LBP in these patients eased with the relief of hip pain and improvement of hip function after THA. Their average LBP VAS score decreased from preoperative (4.13 ± 1.37) to postoperative (1.90 ± 1.44), (p < 0.0001). At the same time, according to the RR calculation formula of the JOA scoring system, the proportion of patients with good treatment response reached 93.46%. Our results show that LBP has been relieved after THA surgery, which is consistent with previous studies [9,10,18]. Although most patients' pain was relieved or even disappeared, there were 9 cases of persistent or worsening pain postoperatively. 8 of them achieved good results after receiving medications or another lumbar spine surgery (Table 3).
To the best of our knowledge, this study is the first to discuss the effects of unilateral and bilateral THA surgery on patients with both hip and lumbar degenerative diseases. In our study, it was found that the follow-up results of patients in the unilateral and bilateral surgery groups were both significantly improved. Although there was no significant difference in preoperative and postoperative Harris and LBP VAS of hip joints between the unilateral surgery group and the bilateral surgery group, it is interesting to find that the LBP VAS of patients who received unilateral THA changed greater and the difference was statistically significant. This means that patients receiving unilateral THA treatment have better pain relief than patients receiving bilateral THA treatment. It has been reported that patients receiving bilateral THA had higher hip pain level preoperatively than that in the unilateral group, but there was no difference in the scores between the two groups after 1 year of surgery, which is somewhat not consistent with our preoperative results of HHS . The difference in preoperative scores may be related to our small sample. Since our study is the first to discuss the effects of unilateral and bilateral THA treatment on these patients, it is impossible to compare the results we obtained with other researchers.
There are many possible reasons for LBP relief after hip joint surgery. We believe that the following reasons may be helpful in the interpretation of the follow-up results obtained in this study: (1) some studies have shown that THA may help improve the parameters of the spine and pelvis of the patient to restore the balance of the sagittal plane of the spine. Such changes may relieve low back pain and improve lumbar function [20–23]. (2) Changes in walking posture and daily life activities of patients after hip joint surgery can correct the poor postures leading to spinal diseases. (3) After hip surgery, hip pain is effectively relieved, and the quality of life is improved, which relieves the tension and anxiety caused by the patient's pain, thereby reducing the impact of LBP on the patient. However, the mechanism for the relief of LBP after THA is complicated, which requires more in-depth study and investigation to expound. In particular, the pain relief in the unilateral surgery group is more obvious, which may become a new breakthrough in exploring the relief of low back pain after THA.
Offierski and MacNab first described this connection between hip osteoarthritis (OA) and spine disease as hip spine syndrome (HSS) in 1983. Failure to recognize this close pathological relationship between the spine and hip joint may delay treatment and lead to unsatisfactory surgical outcomes of the hip or spine [25, 26]. Some patients with hip disease and lumbar degenerative disease may show the same or similar symptoms: hip and lower limb pain, sometimes including pain around the knee, gait abnormalities, changes in the sagittal sequence of the lumbar spine, and low back pain symptom. Many literatures reported that the sagittal imbalance of the spine is correlated with low back pain and hip symptoms, and a variety of measurement methods have been used to confirm. Therefore, the facts above will cause great trouble for joint surgeons to do diagnosis. What’s more, in the treatment of such patients, the problem on which of hip or lumbar spine surgery is first will arise. So far, the sequence of surgery for patients with hip osteoarthritis and lumbar degenerative disease has been controversial.
Previous studies have shown that the surgical sequence may bring different effects to patients [8, 11, 27, 28]. There is no doubt that THA can effectively relieve pain and restore function in patients with advanced hip arthritis [11, 29, 30]. At the same time, some related studies have shown that patients with coexisting hip and lumbar degenerative diseases have treated lumbar diseases after THA [8, 10, 28], and they recommend hip surgery first. Ben-Gallim et al. published a study on the intervention of patients with LBP and hip OA. In this study, 25 patients were evaluated with pain and function scores before and after THA. All results showed a statistically significant improvement after THA. The authors concluded that THA relieved LBP and recommended hip surgery first . However, since a small sample in this study may be considered a defect. In addition, another shortcoming of their study is that the patients they studied did not indicate whether there were pathological changes in the lumbar spine, which is very important for the interpretation of the results. Another study also found that patients with a history of lumbar spine fusion surgery to undergo THA had worse early outcomes and higher rates of complications and reoperation .
Combined with our follow-up results, for diagnosis and surgical treatment of patients with hip joint disease and lumbar degenerative disease, we suggest that:
We should focus on symptoms. In people with hips with pathological changes, the most common site of pain is in the buttocks, followed by thighs and groins . However, lumbar degenerative disease can also lead to lower limb pain and dysfunction, which will lead to overlapping symptoms of the hip joint disease and lumbar degenerative disease, and needs further identification [32–34]. Detailed physical examination is helpful to the diagnosis of the disease. Patients with hip OA usually have inguinal pain, claudication or hip internal rotation limitation, which can induce lower limb pain during weight-bearing, hip internal rotation and external rotation, and lower limb rolling test . Imaging examination can also provide further diagnostic information. Patients with hip discomfort can be examined by X-ray at the first visit, pathological changes of hip osteoarthritis include osteophyte hyperplasia at the edge of the femoral head and acetabular fossa, subchondral bone cyst formation and joint space stenosis  or early osteonecrosis through MRI examination [37, 38]. At the same time, it is necessary to identify the lesions around the hip joint, such as acetabular dysplasia, glenoid lip tear, round ligament tear, synovitis, trochanteric bursitis, etc. If the cause of the current symptoms can be determined before the operation, then appropriate treatment can be carried out. However when there are pathological changes in the hip joint and spine, we recommend THA first. But patients also need to be told that performing surgery on one anatomical site can relieve the symptoms, but may also exacerbate symptoms in another. And the following situations need to be considered separately, serious lumbar degenerative diseases, such as cauda equina compression, lumbar spondylolisthesis leading to significant spinal canal stenosis. These patients need lumbar surgery first, but they also need to receive THA following the lumbar surgery, because the symptoms caused by hip joint diseases will not be relieved before THA.
This retrospective study discusses the effect of THA on lumbar disease and analyzes for the first time the effect of unilateral and bilateral THA surgery on such patients. Meanwhile, this study used effective and reliable questionnaire for function and pain, with each patient as his/her own self-control. This study also has limitations. The most important limitation is that we did not analyze the imaging data of spine and pelvis in these patients after hip surgery, which may help us to further explore the pain relief mechanism. The next step of our study plan is to follow them up for a long time to see which patients need to undergo lumbar surgery following the THA. These limitations should be taken into consideration in interpreting our results and should be addressed in future studies.