Cementless Hip Replacement

  • Over the last two decades, several Un-cemented or Cementless short stem hip replacement options have been designed.
  • The goals of conservative stems include: the spearing of the trochanteric bone stock; a more physiological loading in the proximal femur reducing the risk of stress shielding; and to avoid a long stem into the diaphysis preventing impingement with the femoral cortex and thigh pain.

Short Stem vs Standard Hip Replacement

In general, short stem hip replacement implants are designed to require less removal of bone.
This serves a dual purpose of preserving the bone for future revision surgery while providing a postoperative state closely mimicking the originally functioning hip joint.
Preserving the bone will certainly be important for “younger more active patients” who may need further surgeries.
Specifically, preservation of femoral neck and a properly designed short stem implant allow for correct stress distribution and avoid complications.
The short stem hip replacement implant allows for the normal physiologic state of load transfer throughout the hip joint.
Several Un-cemented or cementless short stem hip replacement options have been designed.

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Short Stem Bone Sparing Hip Replacement

Hip Replacement Patient demographics and expectations have changed, Short Stem Bone Sparing Hip Replacement serves that need.
Being younger, more active and wanting to return to their normal way of life quicker and without compromise,
these patients require an implant that overcomes the limitations of conventional hip replacement.Bone Preserving Hip Replacement

MiniHip™ Short Stem Bone Sparing Hip Replacement is designed to give patients all the advantages of a traditional total hip replacement with the added benefit of preserving the natural anatomy, offering a solution that is an ideal intervention for a patient requiring treatment options into the second, third and fourth decade.

MiniHip™ Short Stem Bone Sparing Hip Replacement is designed to provide the bone preserving benefits of hip resurfacing with the stability of traditional total hip replacement

  • Typically mid-neck resection, defined from the centre of rotation
  • Trochanter conserving, neck preserving and diaphyseal sparing
  • Promotes physiological loading

MiniHip™  Short Stem Bone Sparing Hip Replacement has shown 99.5% survivorship at 3 years for aseptic loosening and has been awarded 3A rating for clinical excellence by the Orthopaedic Data Evaluation Panel (ODEP).

MiniHip™ Bone Sparing Hip Replacement is designed to preserve significantly more bone stock in the femoral neck, trochanter and diaphyseal region in comparison to other short and conventional stems, helping to promote more natural, physiological loading.Bone Preserving Hip Replacement

1. Trochanter conserving MiniHip™ is designed to follow the natural anatomy: there is no lateral flare and the entry point avoids the greater trochanter.

3. Neck preserving MiniHip™ neck resection is intended to preserve the neck and calcar to assist in promoting more natural physiological loading, unlike conventional Total Hip Replacement.

2. Diaphyseal sparing The length and design of MiniHip™ allows for more bone preservation of the medullary canal than traditional Total Hip Replacement. In addition, the distal tip of MiniHip™ Bone Preserving Hip Replacement is polished to reduce the risk of an increase in bone mineral density from occurring at this point.

Hemispherical titanium shell designed for excellent initial press-fit and long-term stability.
Biomimetic cementless coating technology.

  • Calcium phosphate (CaP) coating with a microcrystalline structure
  • Maintains substrate surface roughness, providing a large area for osseointegration
  • Room temperature electrolytic deposition process

Minimally Invasive Anterior Approach – Preserving Soft Tissue

MiniHip™ is an ideal implant for use with a direct anterior approach hip replacement, soft tissue sparing procedure, as it follows the natural anatomy by going ‘round the corner’ of the calcar.
Direct anterior approach patients have reported earlier discharge and return to an active life as compared to patients who receive the posterior approach.
The MiniHip™ Bone Preserving Hip Replacement implant and MIAA™ instrumentation systems are ideally suited to direct anterior, helping to facilitate patient recovery and a faster return to activity.

Restoring Biomechanics

MiniHip™ Hip Replacement offers a unique way of restoring biomechanics for different patient anatomies.
MiniHip™ is a CT based design and is not constrained in its placement by a conventional, intrusive lateral profile.
This provides a unique solution to restoring the biomechanics of multiple patient anatomies.

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Metha® Short Hip Stem System

The Metha Short Hip Stem is designed to achieve true metaphyseal anchoring for Cementless Total Hip Replacement.Short Stem Hip Replacement
The combination of a bone-conserving design and anatomic accuracy have been proven to meet the needs of both patient and surgeon.

  • The Metha System is available in forged titanium alloy material with a circumferential, proximal titanium plasma spray for pressfit fixation.
  • CCD angle options of 120°, 130° and 135° address various femur types to properly restore joint biomechanics and soft tissue tension.
  • Hip replacement stems with a short stem length and proximal fixation geometry support bone-preserving and muscle-sparing implantation and should also allow for revision surgery with a standard hip stem.
  • A five-year Kaplan-Meier survival rate of 96.7% was determined for the short hip stem prosthesis.

Zimmer Modular Neck Technology

Restoring leg length, joint stability, and range of motion involve distinct surgical challenges. The Zimmer M/L Taper Hip Prosthesis with Kinectiv Technology introduces a system of modular stem and neck components designed to help the surgeon restore the hip joint center intraoperatively by addressing leg length, offset, and version independently. The resulting array of neck options efficiently targets a broad range of male and female patient anatomies.
  • Independent leg-length and offset adjustability to optimize hip joint kinematics and function
  • Independent version adjustability to optimize head center position without affecting proximal stem fit, leg length, or offset
  • Reduced neck geometry and anteverted/retroverted neck options for efficient impingement resolution and enhanced range of motion, which helps to mitigate the risks of accelerated implant wear and dislocation
  • Broad range of head centers better match the wide range of patient anatomies among men and women, help avoid low, bone-sacrificing neck cuts, and provide more opportunities to optimally restore fit and function in the limited-view environment encountered in minimally invasive hip procedures
  • Low-profile implant eases stem insertion and minimizes soft-tissue trauma

Independent Control

Proper offset and leg-length restoration improve total hip replacement function and minimize the risk of dislocation and limp.1,2 For traditional hip systems, leg length and offset are coupled and surgeons are often forced to accept the coincidental change in leg length or offset when making changes intraoperatively (ie, when simply changing the head). The Zimmer M/L Taper Hip Prosthesis with Kinectiv Technology allows surgeons to independently adjust leg length and offset intraoperatively after stem implantation to optimize each dimensional factor without affecting the other.

The Zimmer M/L Taper Hip with Kinectiv Technology also allows independent version adjustments after stem implantation. This facilitates optimal stem position based on the patient’s proximal femoral anatomy while restoring head center position.

Proper offset and leg-length restoration improve total hip replacement function and minimize the risk of dislocation and limp.1,2 For traditional hip systems, leg length and offset are coupled and surgeons are often forced to accept the coincidental change in leg length or offset when making changes intraoperatively (ie, when simply changing the head). The Zimmer M/L Taper Hip Prosthesis with Kinectiv Technology allows surgeons to independently adjust leg length and offset intraoperatively after stem implantation to optimize each dimensional factor without affecting the other.

The Zimmer M/L Taper Hip with Kinectiv Technology also allows independent version adjustments after stem implantation. This facilitates optimal stem position based on the patient’s proximal femoral anatomy while restoring head center position.

Independence

  • Independent leg-length and offset adjustability following stem implantation
  • Leg-length discrepancy is a leading source of patient dissatisfaction in total hip replacement3-6

Version By Design

  • Independent version adjustability following stem implantation
  • Progressively increasing version with decreasing offset to better match patient anatomy
  • Intraoperative range of motion adjustment to resolve impingement and mitigate risk of accelerated implant wear and dislocation

Intraoperative Flexibility

  • No need for surgeon to adjust stem fit to achieve version
  • Version options to optimize stem fit and head center location

Range Of Motion

Impingement of the femoral and acetabular components has been shown to increase risk of dislocation and accelerate wear of the liner.8,9 Since Kinectiv Technology uses +0 heads only, the geometry of each neck component can be specifically optimized for strength and range of motion based on the +0 head length. Kinectiv Technology also eliminates the use of skirted femoral heads that are necessary for the longer offset options of other designs. In addition, the ante/retroverted necks allow the surgeon to adjust version intraoperatively after cup and stem implantation and further fine-tune the range of motion for the patient.

Anteverted And Retroverted Necks

  • When cup placement is not optimal, version options can relieve impingement
  • Version options provide opportunity for surgeon to intraoperatively tune the range of motion to avoid dislocation
  • Dislocation is the second most prevalent complication in total hip replacement, with a 2%-4% incidence10-12
  • Dislocation is a significant financial burden to the healthcare system13

Years of extensive engineering design, laboratory testing, and clinical consultation have been devoted to optimize the structural integrity, wear debris characteristics, and clinical presentation of the implants and instruments.

Strength

The neck and stem components of the Zimmer® M/L Taper Hip Prosthesis with Kinectiv® Modular Neck Technology have passed extensive laboratory fatigue testing, enduring the same stringent requirements as other Zimmer primary hip stems, such as the clinically successful Zimmer M/L Taper Hip Prosthesis and VerSys ® Hip System implants. The strength requirements led to the deliberate design of the proximal stem geometry as well as the amount of version provided by the neck components. The implants for performance fatigue testing were carefully selected via bench testing and exhaustive finite element analysis to ensure that the worst-case combinations of components were tested in anteverted, straight, and retroverted configurations.

Modular Junction Stability

Using long-term clinical retrieval feedback of modular junctions that have been used successfully for many years, Zimmer developed a challenging test to replicate the most aggressive clinical fretting corrosion response. This accelerated corrosion fatigue test development considered test factors including load magnitude, test frequency, number of cycles, solution pH, and solution temperature. Further advances in the test technique allowed for quantification of mass loss from the head, neck, and stem components. Internal mass–loss testing has shown that the combined wear debris of the titanium-titanium Kinectiv Technology junction using an extra-extended offset neck with a +0 cobalt chrome femoral head is less than that of a +10.5 cobalt chrome femoral head on traditional titanium femoral hip stems.1 The use of +0 heads provides a significant advantage in regard to wear debris that can result in amounts less than that produced by traditional stem-head constructs.

Due to the nature of the Kinectiv Technology neck modularity, it is necessary to have a secure lock and fit of the components such that they do not disassemble in vivo. Neck distraction testing was conducted to evaluate the security following simulated mild assembly of the components. The force required to distract the neck components from the stem was greater than that required to distract femoral heads from traditional stem tapers.

Simplicity

With the modular neck there are many more options, but there is also the risk of increased complexity.Kinectiv Technology implants and instrumentation have been designed with significant consultation with surgeons, OR personnel, and sales representatives. The keystone for simplicity is the use of +0 heads only. This eliminates the need for multiple head lengths, complicated charts, and head-size limitations and allows truly independent leg-length and offset adjustment. The intuitive and readily apparent leg-length and offset adjustments improve operative flow. The neck provisional layout within the provisional tray mimics the template of head centers so that one simply needs to select the neck provisional that matches the template head center location.

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