In most cases, a hip TEP is used when the natural hip joint has been damaged by osteoarthritis of the hip joint. Osteoarthritis refers to wear and tear of the cartilage layer on the joint caused by age or incorrect loading. The cartilage wears away, causing the bones to come into direct contact with each other. This wear and tear disease of the hip joint often occurs in patients aged 55 and over.
Coxarthrosis, as the disease is also known, is therefore generally a symptom of old age. Around 10 percent of women and 17 percent of men are diagnosed with this condition, and in a third of those affected, both hip joints are affected. The damage already caused by osteoarthritis of the hip joint is irreversible, meaning that it cannot be reversed by conservative treatment. In most cases, surgery is necessary in the final stage.
Conservative therapies can therefore often only help temporarily. An operation and the use of an artificial joint should therefore be discussed with the doctor in good time.
Wear and tear disease osteoarthritis of the hip joint © catsnfrogs / Fotolia
It has been proven that 77% of patients diagnosed with coxarthrosis already had a previously damaged hip joint. This is referred to as secondary osteoarthritis, or osteoarthritis of secondary origin. Typical secondary arthroses are
- Subluxation coxarthrosis/dysplasia coxarthrosis
- Coxarthrosis following Perthes' disease, epiphysiolysis capitis femoris juvenilis or idiopathic femoral head necrosis
- Protusion coxarthrosis
- Post-coxitic coxarthrosis
- Post-traumatic coxarthrosis
In these cases, hip joint-related complaints can occur early in life. It is therefore not uncommon for young patients to require hip treatment. Hip joint operations are also performed much earlier than in the case of primary wear and tear arthrosis.
Similar to osteoarthritis of other joints, osteoarthritis of the hip joint has three different types of pain:
- Weight-bearing pain - the most common form of pain in hip joint osteoarthritis. The pain occurs and persists during movement and exertion
- Start-up pain - at the beginning of movements. The pain occurs, for example, after standing up and then subsides with further movement.
- Rest pain - discomfort without joint movement. The pain is always present even without movement.
The pain is usually projected into the groin area, into the area of the greater trochanter on the side of the hip joint or into the buttock region . However, the pain often also radiates into the thigh or even the knee joint.
The pain emanating from the diseased hip often causes the patient to adopt a relieving posture. This non-physiological posture is intended to reduce the feeling of pain. However, this can weaken certain muscles (muscle imbalance), resulting in so-called contractures and further restricting mobility.
© Henrie / Fotolia
During the examination by the doctor, there are standardized movement tests (so-called signs) that trigger pain through certain positions. In the case of hip joint arthrosis, this occurs in particular when turning inwards or spreading the hip joint apart . If muscular weakness occurs due to a pain-avoidance malposition, Duchénne and Trendelenburg signs can also be positive. This is often manifested by a typical limp when walking.
In advanced coxarthrosis, there may be significant muscle atrophy (muscle atrophy) and a flexion-external rotation-adduction contracture. Typically, it is then only possible to tie shoes or cut toenails with great difficulty. This misalignment caused by shortened and weakened muscles and tendons also results in a functional shortening of the leg.
X-rays of the diseased hip joint are the basic diagnostic procedure and are routinely used. The hip is x-rayed from the front(anterior-posterior) and from the side(lateral). As a rule, a so-called pelvic overview image is taken to assess the symmetry and leg length.
If the findings are advanced, the X-ray image usually shows all the radiological criteria of osteoarthritis, namely
- narrowing of the joint space,
- sclerosis,
- subchondral cysts and
- osteophyte growths
can be detected. In rare cases , special images of the femoral neck (according to Rippstein) or the acetabular roof (faux profile according to Lequesne) are also used in difficult anatomical conditions, whereby a computer tomogram (possibly with 3D reconstruction) can also provide further information or serve to produce special templates or custom-made implants. Further diagnostics using MRI is usually not required if there are clear signs in the X-ray image, but can provide additional information in individual cases.
© dimdimich / Fotolia
Conservative therapy should be used in the early stages of osteoarthritis.
Sports with movement sequences without compression are recommended, such as
- Cycling,
- swimming or
- gymnastics.
If you are overweight, weight reduction is strongly recommended.
Additional support can be achieved through physiotherapeutic movement exercises against contractures and manual therapy. Due to the often mechanical background to the development of the symptoms, in addition to the inflammatory characteristics, it is not uncommon for symptoms to increase during physiotherapy.
If this does not lead to adequate pain relief, the joint capsule can be infiltrated with a local anesthetic, including cortisone. However, this can only lead to a temporary improvement in symptoms. In the early stages, treatment with hyaluronic acid can also be attempted.
Long-term pain therapy with non-steroidal anti-inflammatory drugs is very common, but can be harmful to the gastrointestinal tract or kidneys due to the side effects. More stomach-friendly selective COX-2 inhibitors are also used, but are not suitable for every patient due to the possible cardiopulmonary side effects.
The prognosis or course of the disease in coxarthrosis varies greatly from patient to patient and is difficult to predict. The majority of coxarthrosis patients require surgery in the final stage.
One of the most common congenital hip joint deformities that can lead to secondary hip joint arthrosis is hip dysplasia. This results in a reduced roofing of the femoral head in conjunction with a twisting of the femoral neck. If this is discovered early, joint-preserving surgery may be able to help.
Joint-preserving operations are subdivided into osteotomies in the area of the thigh bone(femur) and the pelvis.
Intertrochanteric femoral osteotomies correct malalignments in the area of the proximal femur and thus ensure a reduction in transarticular pressure, a re-centring of the force flow and an optimization of the torques.
Realignment osteotomies can be
- varus,
- valgizing,
- extending,
- derotating,
- inflecting or
- in combination
are performed. Osteotomies in the pelvic region aim to correct a lack of roofing of the femoral head and the associated punctual loading and overloading of the articular cartilage. These include Salter and Chiari surgery and triple osteotomy.
It should be noted that these surgical techniques are only of long-term benefit to patients who still have intact articular cartilage. Third and fourth-degree osteoarthritis with significant cartilage damage therefore precludes joint-preserving surgery.
In a total hip replacement (TEP), i.e. a complete hip joint replacement using an endoprosthesis, the surgeon chooses the surgical method, the implants and their anchoring mechanisms.
When making this decision, the surgeon should
- the degree of osteoarthritis,
- the anatomy of the hip,
- secondary diseases,
- age and
- habits and environment
of the patient. The following sections provide an overview of open and minimally invasive surgical techniques and various types of prosthesis.
Approaches to the hip joint: conventional or minimally invasive
There are several standard approaches to the hip joint, which require the patient to be in the supine or lateral position depending on the incision.
With the lateral approach, the patient can be operated on in the supine or lateral position. In this case, the incision is made over the area of the greatertrochanter and requires cutting through the iliotibial tract and part of the gluteal muscles(glutei medius and minimus muscles).
In the posterior (dorsal) approach, the incision is projected dorsally of the trochanteric massif, which requires the patient to be positioned laterally. Here too, muscles(piriformis muscle) must be detached and later refixed.
In modern hip arthroplasty, these approaches and procedures are often avoided today.
Minimally invasive implantation procedures
Newer minimally invasive implantation procedures, on the other hand, spare soft tissue structures such as the iliotibial tract and the important gluteal muscles.
They are usually performed from the front (AMIS) or from the front and side (ALMIS) through so-called muscle gaps. They are characterized by the complete avoidance of partial, subtotal or total separation or detachment of the musculature and thus make a decisive contribution to mobilizing patients more quickly postoperatively and preventing muscular insufficiencies.
Watch the video below to see how a hip TEP is performed:
The individual implants differ in a variety of parameters, such as
- Material (titanium and its alloys, cobalt-based alloys, steel)
- Cemented or cement-free
- Coating (pure titanium, hydroxyapatite)
- Surface structure (micro- or macro-structuring)
- Shank-neck angle (CCD angle)
- Shape (short stem, straight stem, anatomical stem)
- Distance of the center of rotation to the stem axis
A basic distinction is made between cemented and uncemented cups , whereby the cemented variants are mostly available as polyethylene monoblock variants, while the cementless cups have a metallic cup shell and are implanted using press-fit anchoring or screw anchoring.
A variety of material combinations can be used as a sliding pairing (cup inlay/prosthesis head), each of which has advantages and disadvantages. In modern hip endoprosthetics, highly cross-linked polyethylene (PE)/ceramic and ceramic/ceramic bearing couples are used as standard.
Cementless endoprosthetics for a hip TEP
With this implantation technique , a press fit or form fit is achieved by preparing the corticocancellous prosthesis bearing by means of milling (cup of the prosthesis) or so-called impactors (prosthesis stem) after the prosthesis is subsequently inserted. This "clamping" of the hip TEP achieves primary stability, which enables secondary ingrowth of cancellous bone structures. Immediate loading of the prosthesis is possible.
With this type of anchoring, a healthy bone matrix is a prerequisite for good long-term results. However, osteoporosis or bone metabolism disorders of any origin are contraindications, i.e. the endoprosthesis cannot be inserted without cement.
With hip stems, the design of the prosthesis determines the flow of force and therefore the load on the bone surrounding the prosthesis and its remodeling processes.
Short stem prostheses apply the force in the area of the femoral neck, which results in a significant increase in bone density in this area, whereas with straight stem prostheses the flow of force is well below the femoral neck, which in the long term leads to bone loss in the area of the femoral neck and the trochanteres due to inactivity. This can lead to problems during replacement operations. Furthermore, the minimally invasive approaches to the hip joint can be optimally utilized due to the short and round design of the short stem prostheses.
Cemented endoprosthetics for a hip TEP
A synthetic material(bone cement) serves as an interface between the bone matrix and the hip TEP. After implantation, the hip TEP can be fully loaded immediately.
This implantation technique is used in patients in whom a cementless endoprosthesis is not indicated due to reduced bone quality/density, e.g. osteoporosis.
Hybrid endoprosthetics for a hip TEP
A hybrid form of cementless and cemented endoprosthetics is used here, which combines the respective advantages of both implantation techniques.
The acetabulum is often implanted without cement, as metabolic bone disorders with a decrease in bone density only manifest themselves late in the area of the acetabulum. The stem, on the other hand, is cemented and, thanks to the bone cement, achieves an immediately load-bearing connection, even to bone that has already been reduced in quality. Postoperative full weight-bearing is also possible here.
In hip arthroplasty, specialists in orthopaedics and trauma surgery generally specialize entirely in the hip joint and its surgical therapies such as joint replacement and total hip arthroplasty.
