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 Table of Contents  
Year : 2022  |  Volume : 37  |  Issue : 2  |  Page : 55-58

Comparison between outcomes of small head and large head prosthesis use in total hip arthroplasty

Department of Orthopaedics, S. N. Medical College, Agra, Uttar Pradesh, India

Date of Submission03-Aug-2022
Date of Acceptance06-Sep-2022
Date of Web Publication19-Oct-2022

Correspondence Address:
Ashutosh Verma
Department of Orthopaedics, S. N. Medical College, Agra, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jbjd.jbjd_15_22

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Introduction: Total hip replacement (THR) currently uses a various size of head and bearing. These days the most common head diameter used in the THR is 32 mm. The purpose of our study is to compare the functional and radiographic evaluation of outcomes of two groups of patients undergoing the THR, received either small diameter (≤28 mm) or large diameter (≥32 mm) femoral head prosthesis. Materials and Methods: This was an interventional prospective study done between September 2018 and August 2020. The diameter of femoral head sizes 32 mm and 28 mm was used in this study. At definite intervals, patients were regularly followed and specifically assessed for functional and radiographic evaluation. Results: During follow-up of patients with 32-mm femoral head diameter excellent functional results were achieved as graded by Harris hip score (P < 0.0001). No patients showed any complications in the large diameter femoral head group. Conclusions: Large femoral head diameter prosthesis may lead to more stability, range of motion, wear rate, and reducing the complications of revision surgery, but with small diameter femoral head, there is an increased chance of dislocation, impingement, and more complications.

Keywords: Harris hip score, larger femoral head, smaller femoral head, total hip replacement

How to cite this article:
Mittal V, Pal CP, Chahar HS, Sadana A, Verma A, Patel J. Comparison between outcomes of small head and large head prosthesis use in total hip arthroplasty. J Bone Joint Dis 2022;37:55-8

How to cite this URL:
Mittal V, Pal CP, Chahar HS, Sadana A, Verma A, Patel J. Comparison between outcomes of small head and large head prosthesis use in total hip arthroplasty. J Bone Joint Dis [serial online] 2022 [cited 2022 Nov 29];37:55-8. Available from: http://www.jbjd.in/text.asp?2022/37/2/55/358795

  Introduction Top

Total hip replacement (THR) is defined as a surgical procedure, which will alleviate from the deformity and painful hip condition caused by various hip pathologies such as fracture, hip dislocation, various arthritic hips, and few congenital deformities. In this procedure, diseased bone and cartilage of hip are surgically replaced with appropriate hip prosthesis. This hip prosthesis is artificial and made up of different materials such as metals, poly methyl methacrylate, etc. Hip joint is a ball and socket joint in which the socket is acetabulum (cup-shaped pelvic bone) and the ball is the head and neck of thigh bone (femur). This process involves the surgical removal of the damaged ball and socket joint and replacing them with a metal ball and stem inserted into femur bone and an artificial ceramic cup socket. The metallic artificial ball with stem and cup system is called as total hip prosthesis. The replacement procedure of the total hip prosthesis may be done in three ways:

  • Cemented THR,

  • Hybrid, and

  • Cementless THR.

  • The original femoral head diameter is from 39 to 55 mm, with females had lower head sizes seen. At the time of invention of hip replacement prosthesis, artificial head diameter was designed as a copy of native femoral head diameter and design. Currently, there is no theory of small diameter and large diameter femoral head sizes. We suggest a classification of femoral head sizes:

    • ➢ Small femoral head: 22–28 mm,

    • ➢ Large femoral head: ≥32 mm, and

    • ➢ Anatomical head: in this artificial head, diameter is similar to a patient’s original femoral head size.

    Currently, various femoral head sizes and bearing types are used in the THR procedure. In achieving normal hip range of motion of artificial hip joint system and its stability, femoral head diameter plays a significant role during planning phase. These parameters together in favour with increases in the diameter of the femoral head[1] and it is important at the production phase that plan to reach the maximum outer diameter are equilibrium with aims to create the minimum achievable roughness, in order to reduce friction and wear rate.

    In 1960s, 22-mm femoral head size was used, which gradually increased to 28 mm in 1990s and after that 32 mm in mid 2000s. After mid-2000s, the use of 36-mm head diameter had increased as stated by different registry reports. Today the most common head diameter in THR is 32 mm, as stated by reports from the majority of the registries.[2] In our study, the THR with metal on poly, ceramic on poly, and ceramic on ceramic (CoC) bearings with 28 mm or 32 mm head diameter is comparatively evaluated in respect of functional outcomes after replacement, range of motion of hip, dislocation rate of artificial head, wear rate, taper corrosion, and groin pain during follow-up. The purpose of the this study was to compare the intra- and postoperative as well as follow-up results in two same groups of patients who taken either large diameter (≥32 mm) or small diameter femoral head (28 mm) after the THR in terms of clinical, functional, and radiological outcomes.

      Materials and Methods Top

    A prospective study on 40 total hip arthroplasty was conducted between September 2018 and August 2020. Patients included in this study were with degenerative joint pathology such as rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis, avascular necrosis (AVN) of hip, posttraumatic arthritis, pelvis fractures, and hip dysplasia in which THR required and giving written consent to participate in complete investigational and study procedures. Patients with medical comorbidities and active sepsis in hip joint, and age of patients <18 years were excluded from the study. For all prospective cases, a detailed clinical history was recorded with a special attention to the duration of injury, the mechanism of injury, and the nature of injury. Also a history of any treatment or drugs received before reporting was noted. The examination of the whole body was carried out to exclude any concomitant illness.

    Preoperatively, patients were kept on skin/skeletal traction in case of trauma, to relieve pain and to correct deformity. Informed and written consent had been taken. Patients were educated for quadriceps exercise, active finger movement, and breathing exercises. Drugs such as aspirin (if taking) are stopped 7–10 days prior to the operative procedure.

  • Skin around the affected hip was examined for any local infections, inflammation, and scar.

  • Trendelenburg test was done for checking the strength of abductors of hip and assessment of limb length discrepancy and fixed deformity in hip or knee.

  • Hip should be operated before knee, if both hip and knee are requiring replacement surgery.

  • Status of the hip is rated preoperatively by modified Harris Hip Scoring.

  • The planning before procedure is done by x-ray assessment and templating. In x-ray assessment, we determine appropriate stem size, medullary canal for optimal stem positioning, condition of acetabulum, and shortening of limb. The objective of preoperative templating is to detect the implant type, required neck length, femoral offset, and correct size of acetabular cup. X-rays of anteroposterior and lateral views of the affected hip with thigh are the minimum requirement for assessment. However, in few cases, x-rays of lumbar spine and ipsilateral knee are also required. The antibiotics are administered in night before operation, 30 min before skin incision prior to the procedure, and 2 h after the operative procedure.

    In the immediate postoperative time, affected hip kept in approximately 15° abduction by using a triangular pillow between lower limb and prevent extra flexion. Rehabilitation should be started 1 day after operation ideally. In rehabilitation process, patients should be motivated and taught the appropriate exercises and goals, and informed about precautionary measures. In the preoperative period, patients were instructed regarding the use of supportive device, appropriate transfer mechanism, and hip dislocation after replacement. If preoperatively the fixed flexion deformity is present, then hip extension exercises are started. By early flexing the opposite hip with maintaining the affected hip flat on couch (Thomus test), hip flexors stretching exercises are started.

    Partial weight bearing was done after 3 days postoperatively in the cemented THR. In the cementless THR, weight bearing was allowed after 45 days. Quadriceps exercises were mostly initiated the second postoperative day, whereas knee bending is done at 6–8 postoperative days. Skin stitches were removed after 12 days. Patients should be warned about activities such as squatting, cross leg sitting, and position that produces stress and repetitive impact. Such activities increase the risk of dislocation and failure of replacement procedure. Postoperative antibiotics were given. Patients were asked to attend outpatient department for exercises and regular follow-up. Clinical and functional evaluation was done using Harris hip score and radiologically at 2 weeks and thereafter 4 weekly. A detailed clinical analysis was carried out in terms of function, mobility, walking, pain, and complications at the time of each follow-up.

      Results Top

    In our study, a total of 36 patients (40 hips) were studied; out of them, 21 (58.33%) patients were male and rest 15 (41.67%) patients were females. Out of 40 hips studied, six (15%) hips were of chronic osteoarthritis; 22 (55%) hips of AVN of the head of femur; one (2.5%) hip of fracture of the neck of femur with nonunion; six (15%) hips of fracture of the neck of femur with implant failure; and five (12.5%) hips of tubercular hip. Out of 40 hips studied, 13 (32.5%) cases were between 20 and 30 years; 11 (27.5%) cases were between 31 and 40 years; three (7.5%) cases were between 41 and 50 years; eight (20%) cases were between 51 and 60 years; and five (12.5%) cases were more than 60 years; however the mean age of patients is 34.7 years. Out of 40 hips studied, in 15 (37.50%) hip, head size 28 mm was used and for rest 25 hips (62.50%), head size 32 mm was used. Functional assessment of our study was done using modified Harris hip score pre- and postoperatively as shown in [Table 1] and [Table 2].
    Table 1: Preoperative Harris hip score

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    Table 2: Harris hip score at final follow-up

    Click here to view

    It shows that there was significantly no difference in Harris hip score between the head sizes preoperatively and that there was a significant difference in Harris hip score between the head sizes of 32 mm and 28 mm postoperatively.

    Functional outcomes with the use of 32 mm head had an excellent result in 52.00% of patients and good in 48.00%. With the use of 28-mm head, we had a good result in 60.00% of patients, fair in 26.67% of patients, and poor in 13.33% of patients, which is depicted in [Figure 1].
    Figure 1: Functional outcomes of the THR in large and small head prosthesis

    Click here to view

    There were no intra- and postoperative complications in this study. None of the patients showed any radiographic signs of loosening at the final follow-up. No patients showed any complications in large diameter femoral head group.

      Discussion Top

    The original femoral head diameter in female and male is approximately 48 mm and 55 mm, respectively. For better functional results and anatomically, it says that restoring the original femoral head size. However, clinical studies have not been able to demonstrate a statistically significant increase in the hip function in terms of various patient-reported outcomes,[3] clinical outcome score, and gait function in head sizes >32 mm or 36 mm. In our study, preoperatively, mean Harris hip score was 46.53 and 45.56 with 28 and 32 mm head, respectively, which increases to 79.53 and 89.28 at the final follow-up after procedure.

    The range of movement of hip joint after the THR mostly depends on the head diameter of prosthesis used. Other factors such as condition of hip, surgical technique, and preoperative specific factors like obesity, preoperative hip stiffness, surgical approach, intraoperative soft-tissue release and repair, implant positioning, implant design, and postoperative rehabilitation are also responsible for postoperative range of motion. During the procedure, soft-tissue release decides the maximal range of motion of hip that might be restricted by soft-tissue repair and impingement. In our study, as the femoral head size increases in THR, a greater range of motion achieved postoperatively. This is correlated with a study by Matsushita et al.,[4] in which after-procedure measurements showed a more range of motion in the THR with 32 mm as compared to 28 mm heads. However, this is not confirmed in any other study where the intraoperative measurements[2] were applied by the author and showed that femoral offset was responsible for an increase in the range of movement of hip, irrespective of head diameter changing from 28 mm to 32 mm head prosthesis. A study by Sultan et al.[5] showed that increasing the head size from 28 mm to 32 mm usually increments in the range of motion by 8.2 degree before impingement and subsequent dislocation.

    Large femoral head diameter associated with the increased range of motion of hip and more jumping distance should lower the risk of hip dislocation after hip replacement. In a recently published study[6] from the Australian Registry, a late dislocation after primary THR performed with 28 mm, 32 mm, and 36 mm metal on poly, ceramic on poly, and CoC bearings was investigated. Kelley et al.[7] showed a more dislocation rate with 28 mm heads in comparison to 32 mm femoral heads. They also found that with a large acetabular cup when small femoral head diameter was used, there is a further increased chance of unstability. All approaches of operative techniques had decreased chance of dislocation with large femoral head diameter prosthesis. Crowninshield et al.[8] study showed that more femoral head diameter in a total hip arthroplasty with a fixed acetabular abduction angle increases the jumping distance or vertical displacement before impingement and dislocation.

    Wear rate and taper corrosion are two main concerns with large femoral heads and the longevity of the THR. Meneghini et al.[9] showed a more frictional wear in MoXLPE bearings for femoral head sizes 32 mm and 36 mm as compared to 28 mm. In the above study, when a CoXLPE bearing was used, there was no relationship between wear and femoral head diameter prosthesis. Groin pain following THR can be a symptom suggestive of many complications such as infection, implant loosening, iliopsoas impingement, and oversized or malpositioned acetabular components.[10]

      Conclusions Top

    A 32-mm femoral head diameter prosthesis is most frequently used in the THR. The appropriate head size should posses the more possible hip stability and good hip movement and function with the minimum possible wear rate in an attempt to increase the lifespan of the THR. The longevity of hip function also depends on the implant design, patient’s lifestyle, and surgical techniques. Keeping in mind these things, we should identify the appropriate femoral head diameter that best meets the above described properties. We evaluated the important features associated with a head size of prosthesis like wear rate, dislocation after the THR, hip function, taper corrosion, range of motion of hip, and groin pain due to impingement. In summary, we found that features associated with small and large heads used in the THR were noted in [Table 3].
    Table 3: Various properties in hip prosthesis associated with the head size

    Click here to view

    Larger femoral head size prosthesis from 32 mm to 38 mm showed an increased hip range of movement and stability. However, the effect of femoral head size on the persistent of groin pain after the THR needs further investigation and research. According to this study, we suggest the 32-mm femoral head diameter prosthesis, mostly in young patients where the lifespan of hip replacement is of great importance.

    Financial support and sponsorship


    Conflicts of interest

    There are no conflicts of interest.

      References Top

    Holzwarth U, Cotogno G Total Hip Arthroplasty. Brussels: European Commission; 2012.  Back to cited text no. 1
    Tsikandylakis G, Mohaddes M, Cnudde P, Eskelinen A, Kärrholm J, Rolfson O Head size in primary total hip arthroplasty. EFORT Open Rev 2018;3:225-31.  Back to cited text no. 2
    Girard J Femoral head diameter considerations for primary total hip arthroplasty. Orthop Traumatol Surg Res 2015;101:S25-9.  Back to cited text no. 3
    Matsushita I, Morita Y, Ito Y, Gejo R, Kimura T Activities of daily living after total hip arthroplasty. Is a 32-mm femoral head superior to a 26-mm head for improving daily activities? Int Orthop 2011;35:25-9.  Back to cited text no. 4
    Sultan PG, Tan V, Lai M, Garino JP Independent contribution of elevated-rim acetabular liner and femoral head size to the stability of total hip implants. J Arthroplasty 2002;17:289-92.  Back to cited text no. 5
    Jinno T, Koga D, Asou Y, Morita S, Okawa A, Muneta T Intraoperative evaluation of the effects of femoral component offset and head size on joint stability in total hip arthroplasty. J Orthop Surg (Hong Kong) 2017;25:2309499016684298.  Back to cited text no. 6
    Kelley SS, Lachiewicz PF, Hickman JM, Paterno SM Relationship of femoral head and acetabular size to the prevalence of dislocation. Clin Orthop Relat Res 1998;355:163-70.  Back to cited text no. 7
    Crowninshield RD, Maloney WJ, Wentz DH, Humphrey SM, Blanchard CR Biomechanics of large femoral heads: What they do and don’t do. Clin Orthop Relat Res 2004;429:102-7.  Back to cited text no. 8
    Meneghini RM, Lovro LR, Wallace JM, Ziemba-Davis M Large metal heads and vitamin E polyethylene increase frictional torque in total hip arthroplasty. J Arthroplasty 2016;31:710-4.  Back to cited text no. 9
    Henderson RA, Lachiewicz PF Groin pain after replacement of the hip: Aetiology, evaluation and treatment. J Bone Joint Surg Br 2012;94:145-51.  Back to cited text no. 10


      [Figure 1]

      [Table 1], [Table 2], [Table 3]


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