Broken Austin Moore ProsthesisFatigue or Failure?

Vinod Naneria

Choithram Hospital & Research centre, Indore, India

A broken stem of Austin Moore’s hip prosthesis

Purpose of presentation

Fatigue Failure• It is sure implant failure.

• It requires revision.

• There is significant anterior thigh pain.

• There are loose, hence stem failure occur.

• It has worked for so many years, that’s the reason it has failed.

• Yes…………………………………!

• Just a metal fatigue

• It does not requires any treatment.

• Hip movements are normal.

• Proximal part – femoral head – shaft are rigidly fixed.

• It has worked for so many years – how can it fail?

• No……………………………..!

The debate?

• Broken stem of AMP –

– Is it loose?

– Has it failed after serving for many years?

– Why it broke?

– Is it same as broken stem of a cemented THR?

– Does it need revision?

– Is revision mendatory?

Not loose – Not failed – No revision

Observations

• All AMP were done in young age lasted long.

• Good quality bone support AMP well.

• Bone growth is noted in fenestrations of AMP.

• Hypertrophy of the calcar region noted in all cases.

• There was no sign of loosening in any case.

• There was no sinking of proximal prosthesis in femoral canal.

Observations - THR

• In THR stem brake due to fixed distal part and loose proximal part.

• Since proximal part is loose, it needs revision.

• In contrast to THR, breakage of AMP stem is due to loose distal part and a Fixed proximal part.

Feb 2012

Oct 2013 January 2014

Loose proximally Loose & broken stem

Well fixed stem Loose stem

Broken stem

Observations

• Even in a well fixed prosthesis, there are constant bending strain of cyclic loading leading to remodeling of the proximal femur and to varus setting of the head-neck of prosthesis.

• A broken stem of AMP is a metal fatigue failure.

Observations

• Since proximal part is well fixed, revision is not required.

• The initial pain following breakage of stem is due to change in the distribution of mechanical forces, as the lateral femoral cortex start bearing more load.

Bone in fenestration Bone hypertrophy at the tip Bone hypertrophy lower lateral cortex

Case one

• 18 years old lady had a puerperal sepsis - 1982

• Acute renal shut down ended up in CRF.

• Had fracture neck of femur -1985.

• AMP was done considering failures of internal fixation in CRF patients(Past experience of failure in two cases) and limited life expectancy.

• Had Renal transplant in 1987

• She was 7th case of renal transplant at Choithram.

Case history continue…

• On regular follow up.

• Delivered a baby girl 1991.

• Severe obesity.

• Stem broken noted in 1995 (x-rays)

• Last follow up 2006.

• Had Ca Breast with multiple mets – died 2007.

• No x-ray changes noted between 1995 – 2006.

Case one1995 2006

2006

Case Two

• 54 years old Female

• AMP done out side.

• Had acute onset of anterior thigh pain May 2012.

• A suggestion was given to for Total Replacement out side.

• Seen May 2012 with Broken Stem

• Full range free movements at hip

• Last seen Dec 2012.

Feb 2010

May 2012

Dec 2012

Lateral corticalHypertrophy

Case Two

Case Three

Lateral cortical hypertrophy and migration of loose distal fragment medially

Case Three

• This old man had AMP left hip before 1992 (X-rays)

• He had fracture trochanter on right side –2000.

• DHS was done in 2000.

• Last follow up 2006.

• Rigid fixation by bone in fenestrations.

• Medial migration of distal loose piece.

Case Four

1992

Case four

2000

Case four

2006

Case Five

• 22 years old male had RTA – fracture neck femur. 1986

• Operated by multiple Knowles Pins.

• Broken pins noted – 1988 – fracture united.

• AVN – 1990 – AMP done.

• Pain in anterior thigh 2002 due to broken stem.

• Last follow up 2006.

1986 Knowles pinning Pins breakage 1988

By – Late Prof. V. S. Inamdar

AVN 1990 AMP 1990

By – Late Prof. V. S. Inamdar

2002 2006

Case sixth

• This 82 years old male had an AMP – 1993

• Complains of acute anterior thigh pain since last one month.

• A broken stem noted Sept, 2013.

• Was suggested Total Joint Replacement out side.

• There is no difficulty in ADL.

• Left as such under observation.

Case six

Case seventh

Case eighth

• 36 yrs Male• Bilateral AVN hips• AMP done 1988 rt side at the age of 36 yrs• THR cemented done on left 1990 at the age of 38.• Revision THR for shattered femur 2007• Sciatic palsy• Removal of Memmen plate and wires April 2009.• Removal of THR Sept 2009.• Metal fatigue 2012• Last follow up Nov 2014.

Case Eighth

• Acetabular poly wear 2007.

• Sustained periprosthetic fracture with shattered femur.

• Non cemented “Solution Hip” with Mammamplate and circlage wires + bone grafting of acetabulum.

• Sciatic nerve palsy.

Case Eighth

• Persistent pain in hip

• Plate and wires removed in April 2009

• Pain in knee and hip persisting

• Solution hip system removed for suspected low grade infection Sept. 2009.

• Serial x-rays showing broken amp in Jan 2012.

• Last follow up 2014.

• Sciatic nerve has partially improved.

2000

10 years post THR12 years post AMP

June 2004

Signs of poly wear

Dec 2005

Well fixedExtensive poly wearWaiting for revision

Severe poly wearBadly comminutedVancouver B3Fracture of shaft +Proximal loosening Loose cement Loose prosthesis

June 2007

June 2007

June 2008 April 2009

April 2009

Persistent pain at hip and kneeSonography hip ? Small collectionAspiration – culture negative

Sept 2009

Removal of prosthesis due to pain

Sept 2009

21 years post implantationPain freeWell fixed AMPHypertrophy of CalcarBone in the fenestrationBone at the tip of AMPAmbulation with cane support.Lt. Sciatic nerve improving

Dec 2010

Incidental findingSigns of metal fatigue

2012

Nov 2014

No painNot aware of broken prosthesis

AMP1988 - 2014

Summary & Conclusion

• Broken stem is not a implant failure.

• Broken stem is not a sign of loosening of implant.

• Cyclic loading of bending forces are probably the cause.

• A follow up of cases of broken stem for more than 14 years, did not show any deterioration in fixation of proximal implant.

• There was hypertrophy of the lateral cortex of femur at the site of broken stem.

DISCLAIMER

Information contained and transmitted by this presentation is based on personal experience and collection of cases at Choithram Hospital & Research centre, Indore, India. It is intended for use only by the students of orthopaedic surgery. Views and opinion expressed in this presentation are personal. Depending upon the x-rays and clinical presentations viewers can make their own opinion. For any confusion please contact the sole author for clarification. Every body is allowed to copy or download and use the material best suited to him. I am not responsible for any controversies arise out of this presentation. For any correction or suggestion please contact naneria@yahoo.com