Ours was the largest study of its kind. 1140 (916 female and 224 male) healthy young athletes were recruited, aged between 9 and 17 years - all participating in a variety of organized sport. None had had previous knee injury of any significance. All had participated in organized sport for a mean of 4 years before the date of testing.

We tested their quadriceps and hamstrings strength using an ‘isokinetic’ machine (1030 subjects), videoed their lower limb alignment on a drop-jump (536 subjects) and also compared their limb symmetry in single-leg hop tests (324 subjects).

With regard to strength testing, what we were particularly interested in were the:

• normalized peak torque of quadriceps and hamstrings – that is the maximum strength of each of these muscle groups, if a correction were made to account for their weight (in other words, we calculated what the maximal strength would be if the children had all been the same weight). 
• hamstring: quadriceps ratio – that is the strength of the muscle group which bends (flexes) the knee compared to the strength of the muscle group which straightens (extends) the knee (in other words, in other words whether one muscle group is too strong compared to the other).

The first major finding from this study was that girls reach their maximum hamstring strength by age 11 – a new detection in the medical literature. This is particularly concerning in light of the fact that hamstrings play a major role in protecting the anterior cruciate ligament from injury. Boys reach their maximum hamstring strength by age 14 and, as expected, had significantly greater strength than age-matched girls. For quadriceps strength, girls reached maximum values by age 13 and boys by age 14 and again, boys had much greater strength in this muscle group than age-matched girls.

Actually, we found no statistically significant difference in the hamstrings:quadriceps ratio between genders at any age. Both the boys and the girls showed a decrease in the ratio from 9-17 but we did not find the dramatic difference in genders that other researchers have found in this ratio - which was most likely due to the tremendous number of athletes we tested among the age groups and the fact that most of the athletes were involved in sports year-round.

The second important finding from our study was that there was no difference in lower limb alignment on landing from a drop jump - a high percentage of both males and females in all age categories landed in an overall knock-kneed (valgus) lower extremity alignment. As well, both boys and girls had poor lower limb symmetry during single leg hop tests. While other investigators have speculated that an improper valgus landing position may predispose females to ACL injury, this finding reveals that other factors are more likely to be responsible for the gender disparity in knee ligament injury rates.

After surgery, patients are typically hospitalized for 48 hours to control pain and to initiate the rehabilitation. Appropriate rehabilitation is essential to success. Motion machines and manual stretching by skilled physical therapists are key components in the early hours and days after surgery. Dynamic bracing can also be used to help maintain extension of the knee. The knee cap (patella) and all the tendons to which it attaches must be kept mobile and supple. After discharge from the hospital, daily outpatient physical therapy visits start and may continue for 6 to 8 weeks.

When an individual develops arthrofibrosis, it is important for them to seek a knee specialist who understands the many causes of the problem so that treatment can be targeted at the specific cause. Arthroscopic treatment of knee arthrofibrosis is definitely effective in improving knee range of motion and restoring function, assuming that the surgery is performed properly and with skill. Arthroscopic surgical treatment can be very complex and technically challenging, and it is generally most effective when the underlying problem predominately within the joint. When the scarring is also outside the joint, a combined approach that includes both arthroscopic and open techniques may be indicated. Careful diagnostic evaluation, skillful surgery, and appropriate rehabilitation can be expected to eliminate pain, improve motion, and restore motion in the vast majority of individuals with this problem.

References:
1. Kim D, Gill TJ, Millett PJ. Arthroscopic management of the arthrofibrotic knee. Arthroscopy 2004, Jul;20 Suppl 2:187-94.

2. Millett PJ, Johnson B, Steadman JR. Rehabilitation of the arthrofibrotic knee. American Journal of Orthopaedics, 2003 Nov;32(11):531-8.

3. Millett PJ, Steadman JR: The role of capsular distention in the arthroscopic management of arthrofibrosis of the knee: A technical consideration. Arthroscopy 2001;17:E31.

4. Millett PJ, Warren RF, Wickiewicz TL. Management of motion loss following knee ligament surgery. In Simonian and Wickiewicz (eds). The Adult Knee. Philadelphia: Lippincott, Williams & Wilkins, 2003.

5. Millett PJ, Wickiewicz TL, Warren RF. Motion loss after ligament injuries to the knee. Part II: prevention and treatment. Am J Sports Med 2001; 29:822-8.

6. Millett PJ, Wickiewicz TL, Warren RF. Motion loss after ligamentous injuries to the knee. Part I: Causes. Am J Sports Med 2001; 29:664-75.

7. Millett PJ, Williams RJ 3rd, Wickiewicz TL. Open debridement and soft tissue release as a salvage procedure for the severely arthrofibrotic knee. Am J Sports Med 1999;27:552-61.

Dr. Peter Millett is an Associate Surgeon at the Steadman Hawkins Clinic in Vail, Colorado. He specializes in disorders of the knee, shoulder, and sports medicine. He has a particular interest in arthrofibrosis and ligament injuries of the knee. Dr. Millett holds a faculty appointment at Harvard Medical School and was formerly on the staff at the prestigious Massachusetts General and Brigham & Women’s Hospitals in Boston. He serves as a team physician for the U.S. Ski Team. More information can be found at www.drmillett.com or by emailing him at drmillett (at) steadman-hawkins.com.

(front view of completed hamstring ACL reconstruction)

(side view of completed hamstring ACL reconstruction)

2) Alignment: HIGH TIBIAL OSTEOTOMY (HTO) in which the tibia or shinbone is cut and straightened on an outpatient basis to remove abnormal stresses on the knee




(Pre-op)

(3.5 months post-op)

(view through an arthroscope showing the absent meniscus)

(after an allograft meniscus has been transplanted)

(simultaneous autologous chondrocyte implantation (ACI) and meniscal allograft transplantation (MT)

• there is about a 0.21% chance of dying in the first 30 days after a total knee replacement.


• cemented implants carry a far greater risk than uncemented implants. In this study 47 people died out of the 22,000, and in all of these the cemented variety was used.


• dying is more likely during the first knee replacement than in subsequent procedures which may become necessary to replace the first knee replacement - that probably means that if you have the risk factors, then they are likely to take you out in the first operation and anyone going on to subsequent revision surgery are likely to have lower risk factors in the first place.


• pre-existing lung and heart problems really do matter and must be taken seriously. 43 of the 47 patients who died had pre-existing lung or heart problems. Although not stated, it seems that one might safely conclude that if you do have these problems it would be best to consider an un-cemented replacement rather than a cemented one (the cement is pretty toxic when it is setting and does nasty things to the blood pressure for the first few minutes when it goes in).


• having both knees done at the same time is also riskier than one at a time. Sometimes however, eg. with severe bow legs, it is not practicable to do the two knees at separate times. A bow-legged person given one straight knee during surgery would have trouble rehabilitating as the other leg would be much shorter.


• age seems to be an important factor. 39 of the 47 patients who died were over 70.


• dying during the actual operation is less common than dying after it, so one needs to understand that the first 30 days are all critical.


• women and men seem to fare equally well and gender does not seem to be a real issue.

Refs
1. Parvizi, J et al (2001) Thirty-day mortality after total knee arthroplasty. Journal of Bone and Joint Surgery 83-A, 8, 1157 - 1161

There is strong evidence that acupuncture is very effective for pain in the knee and has been proven to be more effective than sham acupuncture treatment. (Arthritis Rhem, April 1, 2001: 44 (4); 819-25).

How does it work?

Many textbooks have been written regarding the basis of acupuncture and read like an organic chemistry textbook!  To simplify, it appears that the local effect of putting a needle through the skin serves to improve local blood flow to an area that may have relative ischemia (a lack of blood flow), that then benefits greatly from a local improvement in circulation.  This is particularly true for conditions that involve strain and swelling.

With the addition of electrical stimulation, which is frequently used in conjunction with acupuncture, there is proof of local production of beta endorphins, the body’s natural pain killing and pain modulating substance.  It appears that acupuncture provides pain relief by activating the pain modulation system of the body, and changes both the processing as well as the awareness of the painful information at various levels in the central nervous system.  By modulating pain, decreasing the awareness of the incoming pain signals, improving blood flow, improving the production of pain relieving substances, and in general promoting healing in the area of trauma, acupuncture helps to generate improved blood flow resulting in improved healing to the area. 

In my own clinical practice I have found that acupuncture serves as an excellent companion to conventional medical care for many knee conditions. 

Medication management including anti-inflammatory agents, quality physical therapy with muscle lengthening, instructions for stretching and appropriate strengthening of the muscles that surround the knee, as well as appropriate orthopedic intervention when medically necessary for such conditions as instability and meniscal pathology, can all be augmented with appropriate and timely use of acupuncture. 

Where do the needles go?

Typical acupuncture points for knee pain include many points directly surrounding the knee and foot, local tender points within the muscle, and even at remote points in other parts of the body depending on the style of acupuncture and the practitioner performing the acupuncture treatment.  Energy axis style treatment of acupuncture addresses many components of an individual patient’s pain, personality structure, and overall biopsychosocial makeup.  The beauty of acupuncture is the versatility of treatment that can vary greatly from patient to patient and can be effective for a wide range of conditions. 

Does it hurt? Most practitioners use very thin small disposable acupuncture needles that are nearly painless.  While the insertion technique of the practitioner is certainly important, most acupuncturists have excellent skills and the actual insertion of the needle is not painful.  Local points within muscles called Ah Shi points literally grab the needle and pull it down within the muscle.  This can create a sensation of deep ache and difficult to describe unless personally experienced.  Following an acupuncture session and manual stretching, most individuals experience a profound degree of relief if they get such a response. 

How many treatments usually necessary? The average number of treatment sessions varies greatly based on the condition, and the chronicity of the problem, in the individual patient.  In my practice, the patient usually gains benefit with an average number of 8 to 10 treatments.  I initially schedule two visits per week for two weeks and then quickly taper the number of treatments to one session per week, then every other week, and by the time the patient is seen one time per month I usually instruct them to contact me on an as needed basis for control of pain.  Most patients gain additive benefit from each subsequent acupuncture and have longstanding relief without the continuing need for acupuncture services. 

I was trained at UCLA where they instruct to perform an average of six treatment sessions to determine if the patient is a responder to acupuncture.  In the general population there is an approximate 15 percent of individuals who are what we call “non responders” to acupuncture.  These individuals for unknown reasons are not responsive to the typical mediators that cause acupuncture to be effective.  Therefore 85% of the general population is responsive in a positive way to medical acupuncture as a treatment.  I have found these numbers to be true in my personal practice as well. 

In summary, acupuncture can be very helpful for the control of knee pain for many different underlying knee diagnoses.  It is most helpful when used as a companion to conventional medical care, rather than independent of it. 

For more information regarding the style of acupuncture that I practice you may find useful information as well as links at the American Academy for Medical Acupuncture (http://www.aama.org).  The site includes a link on how to find a provider in your geographic area.

While MRI testing is an extraordinary diagnostic tool in certain areas, its accuracy for knee pain and arthritis is arguably one of the greatest myths of our time. In my experience, the odds of coming across a false-positive MRI range from 10 to 100 percent, depending on the knowledge and integrity of the radiologist. The MRI provides nothing more than thin, flat slices of a complex, colorful three-dimensional structure, so it is subject to interpretation and can miss conditions such as arthritis, partial ACL ligament tears, and kneecap mal-alignment.

In The Hands Of The Wrong Orthopedist, The MRI Becomes A License To Operate.

• Grades I, II and III cartilage “tears”
  At the dawn of this new millennium, one is at greater risk of being misdiagnosed with a torn cartilage than at any other time in history. Since the MRI shows only thin shadows of complex structures, small abnormalities might be missed. While a Grade III tear may or may not require surgery, a Grade I or II never does! By reporting grade I and II changes as tears, a radiologist allows the unscrupulous orthopedic surgeon to recommend a surgical procedure. Seeing the word ‘tear’ on the MRI report, most patients readily agree to surgery.
• MRIs can over-read common knee conditions.
  Other knee pain causes such as nagging tendonitis, which is an inflammation of the tendon, and runner’s knee, which is an irritation of the so-called iliotibial band, running along the outside of leg and knee, can be misread on MRIs as torn cartilage. These conditions can be treated without surgery.

X-Rays, costing 1/10 of an MRI, can diagnose arthritis, and “LK-SSS (Limited Knowledge, Suspect Scruples) doctors"
A severe arthritic flare-up will eventually quiet down on its own. A competent physician will prescribe old-fashioned x-rays, usually sufficient to diagnose arthritis or knee mal-alignment, at 1/10 the cost of an MRI. If a patient is over forty years of age, the doctor should make certain the frontal x-rays are taken in a standing position. However, an LK-SS Doctor –- which is how I describe a surgeon with limited knowledge and suspect scruples – uncertain about a diagnosis, and possibly motivated by revenues created by expensive, in-office MRI equipment, might be quick to prescribe an MRI, followed by surgery for a “torn” meniscus. When the patient’s pain persists after the operation, the LK-SS surgeon identifies the problem as arthritis, which should have been detected preoperatively through x-rays and a good physical examination, but was not detectable on an MRI.

Treat Patients, Not Tests
Unfortunately, less emphasis is being placed on patient history and physical exams. Taking the time to really listen to a patient is becoming a lost art. Too often patients, not making the connection between the proliferation of technology and rising health care and insurance costs, feel shortchanged if no MRI is prescribed. The reality is that MRIs, which can run between $500 and $1500 a scan, depending on circumstances, inflate our insurance premiums, and the insurance companies’ ability to pay for other tests and treatments.

What is the answer? - Education! The key to improving health care while holding down prices is twofold: encouraging consumers to be more involved in decisions regarding their own care, and reminding doctors to combine cutting-edge technology with old-fashioned, personalized service.

Luxation/Dislocation
They began with ‘luxation’ – but problems were immediate. The French and German speakers were comfortable talking about ‘luxation’ of which ‘subluxation’ is obviously a lesser form, but all the English speakers never used the term ‘luxation’ at all! They talked of ‘dislocation’ and felt that ‘luxation should be dropped altogether. Not surprisingly the French and German speakers thought that ‘dislocation’ should be dropped in favour of ‘luxation’.

They moved on to examine whether at least the terms were used in the same way, and whether all doctors would understand exactly what was meant when either term was used. But again no, not really. There were three different usages –

• If one said ‘The patient has suffered a dislocation (or luxation)’ all agreed that this meant that there had been a distressing incident where the kneecap had completely derailed (left the ‘trochlear groove’) and stayed there. This would be a sudden and painful event.
• But it was also agreed that the term could be used, too, if the doctor during examination could make it derail (usually emphatically resisted by the patient) although it may never have derailed on its own.
• And thirdly it could be used to describe the findings on X-ray when the kneecap looked derailed, although again the patient may never have suffered any sudden painful event.

The term ‘subluxation’, a lesser form where the kneecap almost derails, was similarly used for something the patient suffers, something the doctor could elicit or an X-ray finding.

So, in other words, a patient can ‘exhibit’ subluxation, but not actually be symptomatic at all. Or may be labelled ‘a subluxer’ but suffer no symptoms. (But a ‘dislocator’ will always be symptomatic, except in the very, very rare case of permanent dislocation).

Then the real ‘biggie’ muddles were put on the table – ‘anterior knee pain’, ‘patellofemoral pain syndrome’ and ‘chondromalacia’. What did they make of these?

Chondromalacia
Let’s start with ‘chondromalacia’.  Thousands of articles on the web confidently talk of the condition of ‘chondromalacia’. The USA even has a specific code for the condition (717.7). But the twenty knee specialist from five countries were all in accord - “CHONDROMALACIA SHOULD NOT BE USED TO DESCRIBE A CLINICAL CONDITION”.

The word means literally ‘cartilage softening’. If it has been shown that abnormal cartilage softening literally exists, then they agree it is valid to use the term, but even then the term should be clarified to avoid confusion. But they recommend instead that ‘cartilage lesion’ is a better term to use.

Anterior Knee Pain/Patellofemoral Pain Syndrome
What about ‘anterior knee pain’?  Like ‘chondromalacia’, this term is vague.  The International Patellofemoral Study Group recommend that the term is best reserved to describe the patient who has yet to be evaluated.

‘Patellofemoral Pain Syndrome’ is used by some practitioners who find no identifiable cause of anterior knee pain.  The Group agree the term should mean just this - it is NOT a diagnosis, merely an indication that the practitioner has not been able to identify the cause of the patient’s pain.

The terminological muddle goes further (see the references), but I imagine you have already got the message - be very careful when you are given a patellar diagnosis that you understand exactly what you are being told because it’s a minefield.

The number of people having total knee replacement is due to massively increase as post-war baby boomers start to hit their sixties, but this is unfortunately occurring at a time when health insurance companies around the world are tightening up on cost containment. The authors recognise that rehabilitation after total knee replacement is long, and insurance companies already do not fund adequate physiotherapy time. This book was written to support the knee replacement patient with practical advice for a full year after surgery.

The first two chapters give an overview of arthritis and current approaches to slowing its progression and improving quality of life. Knee replacement is discussed in some detail - basic design considerations, bilateral knee replacement and how to go about finding a competent surgeon. Question and answer sessions complete each chapter.

There is a useful pre-surgery chapter, advising on getting your home ready for your return from hospital and giving useful exercise regimes for building up strength to facilitate the use of crutches or a walker after surgery.  What to expect once you arrive at the hospital and on the day of your operation are covered in some detail, but detail of the surgical process itself has been deliberately minimised. Potential complications are, however, covered in an appendix.

From this point on the book really fleshes out, and focuses on rehabilitation, taking the reader day by day through carefully chosen exercise regimes, all explained and fully illustrated. Through the early days on the ward, then home, and beyond are all covered in significant detail, using for the greater part readily available household items as rehabilitation aids.

There are several sections on scar management.  Bathroom aids are discussed. Range-of-motion exercises, strengthening exercises, balance exercises, endurance exercises - all are discussed and illustrated, and carefully graduated as time progresses, right the way to a full return to normal activities. Question and answer sessions accompany each chapter, and an index of the exercises is available in its own appendix for ready reference.

This book will be extremely useful to anyone contemplating total knee replacement.

Firstly, would you say I was right? – that the idea of the UniSpacer is that it slots into the gap of a missing meniscus and improves the forces through the knee in order to delay arthritic destruction consequent on previous total meniscectomy?

Dr Trotter: No. It’s more than that. The UniSpacer procedure is relevant to patients with joint space narrowing on one side of the knee, where the joint cartilage (‘articular cartilage’) is becoming damaged by the altered forces through the knee. This is the case whether the meniscus has ever been acutely torn at all.

If the joint space narrowing is on the medial (inner) side the bowing of the leg is called ‘varus’ deformity, and the primarily affected region is termed the ‘medial compartment’ of the knee. The articular cartilage of the medial compartment frequently is either thinner or just softer than normal, especially in the more active, younger end of the spectrum. This often occurs even with an intact meniscus (or rim).

Overall, the key issue is the narrowing of the medial joint space on a standing film. Joint space narrowing often results in increasing pain due to the dysfunctioning cartilage support or ‘bone on bone’ effect. This can lead to instability due to increased joint compression (like a hammer in dish effect) in the stance phase in that compartment.

KNEEguru: You talk about ‘standing’ films. What do you mean?

Dr Trotter: These are X-rays of the knee taken while the patient is standing and bearing their body weight. Varus is sometimes difficult to always pickup on clinical examination. In fact, some people’s knees look almost valgus (knock-kneed) but when you get standing films, you can see medial joint space narrowing. Of course, we must always ensure that the primary problem is from the medial compartment.

KNEEguru: So, summarise that again for us, please.

Dr Trotter: Sure - “The ‘spacer’ is optimal for that symptomatic patient who has failed reasonable non-operative treatment and who has a tendency for slight (or sometimes dramatic) medial joint space narrowing on x-rays."

We look especially closely at the medial joint space in standing films. If the patient points to the anterior medial (inner front) knee (although often they can’t quite localize the pain site quite that well) and, if the medial joint space is decreased as compared to the lateral (outer) space, then they are quite likely (if the ligaments are intact or repaired) a good candidate for symptom relief from a UniSpacer.

KNEEguru: Can you tell us when the first UniSpacer procedure was performed, and how many patients have had this procedure so far?

Dr Trotter: The first UniSpacer was performed in May, 2000 and there have been thousands performed globally, including in both knees of a sizable number of patients.

KNEEguru: But it is still early days and the medical literature will still be sparse. How long in your opinion does a new operation like this take to fully evaluate once surgeons start using it?

Dr Trotter: The ‘best’ medical studies are typically those that have a large enough number of patients that have been clinically followed for a long enough period so that a trend or pattern (or lack thereof) appears to have emerged. The standards of just what constitutes ‘large enough’ and ‘long enough’ can vary depending upon the branch of medicine and/or form of treatment being assessed.

However, remember that the UniSpacer is a form of ‘interpositional arthroplasty’ (a joint replacement between the femur and tibia), and the concept of interpositional arthroplasty predates the early versions of the total knee replacement procedures. Therefore, our understanding of many of the issues goes back well before May 2000.

KNEEguru: Can you tell us more about that.

Dr Trotter: Certainly. In the 50’s and 60’s, many patients were treated with metallic tibial hemiarthroplasty, including implants developed by MacIntosh and McKeever. These implants required relatively minimal upper tibial (lower half of the joint space) bone resection and occasionally required the removal of minimal femoral condyle (upper half of joint) to allow for proper function.

MacIntosh and Hunter reported, in 1972 JBJS [Journal of Bone and Joint Surgery], an average follow-up of 3.5 years, 135 implants. They reported that 80% of the patients with OA (osteoarthritis) had good results.

Three authors have reported on their experiences with McKeever Hemiarthroplasties in OA patients. The studies, published in 1972, 1985 and 1985 JBJS reported as good-excellent results in the 3 studies:

1. 89% (3 year average follow up),
2. 70% (8 yr. av. f/u) and 79% in pts. under 64, and
3. 75% (5 yr. av. f/u)

Overall however, as compared with partial (two-piece unicompartmental) or with total knee replacement, available data on the UniSpacer procedure is significantly less.

Despite that, the relatively early results of the refined UniSpacer procedure (including, in my experience, the combination of UniSpacer with removal of a large portion of the synovial tissue that contributes to the production of excessive arthritic fluid/inflammation) are promising.

KNEEguru: In June 2003 a Dr. Friedman presented a paper quoting early reports of 8-10% dislocation, and that he himself had to revise 23% of his own Unispacer cases. Have things moved on? Were the earliest users using a different technique to your current technique?

Dr Trotter: Absolutely. The rate of dislocation has plummeted to between 1-3% in the hands of experienced users of the refined/modern surgical technique. The overall revision rate has likewise been dramatically reduced to a similar infrequent range, again in the hands of those specially trained surgeons that have learned from the education and experience of the earliest pioneers.

Today, not only have we benefited from a far better experiential base regarding UniSpacer implant sizing; we also have benefited from an improved surgical technique that addresses issues such as the fluid producing knee tissue known as the synovium. At the Center for Sports Orthopaedics, SC, we have specifically added an extra process in the UniSpacer technique in order to remove a significant portion of this tissue that can be associated with inflammation in patients with osteoarthritis. Early results of this UniSpacer-synovial ablation combination appear quite promising.

KNEEguru: I understand that patient selection has been shown to be very important in this procedure.  What are your own selection criteria?

Dr Trotter: To date, we have performed the UniSpacer technique in patients ranging from a 33 year old pediatric nurse to a still active 88 year old (who recently requested and now has a UniSpacer in each knee.) At the Center for Sports Orthopaedics, UniSpacer candidacy is determined not by age but by the anatomy of a patient’s arthritic knee.

Appropriate candidates for the procedure include patients that:

• have moderate to severe knee pain associated with activities.  The pain is often (but not always) localizable to the inner aspect of the knee. “It hurts here doc” is a common refrain heard in our center.

• We routinely obtain standing knee x-rays to determine if the patient has a narrowed medial (inner knee) joint space upon weight-bearing. During the evaluation, if the patient’s medical history, exam findings and x-rays all support that the overwhelming majority of pain is coming from the medial compartment of the knee joint, then the patient would be a candidate.

• When a patient has not had adequate relief with oral medications or injectibles and/or bracing, then he or she would be a potential candidate.

• It’s important to emphasize that a patient’s ACL (anterior cruciate ligament) must be intact (either never injured or repaired).

• In the operating room, we also surgically address certain patella-femoral joint pain with a release of the lateral retinacular tissue adjacent to the kneecap. This tends to both realign and untether the patella from the same chronic pressure producing region. Lateral compartment disease (if applicable) can be also addressed during the initial arthroscopic phase of the UniSpacer procedure.

Having the largest series of UniSpacer patients in the Midwest region of the United States, we are continually cognizant of optimizing patient selection. Also, postoperative therapy techniques are important and include cooling of the knee, minimal to no bracing, and, the use of a CPM (continuous passive motion) device for optimizing knee motion.

KNEEguru: So my initial assumptions were clearly quite wrong. The Unispacer has a broad application and is not just for patients who have had a medial meniscectomy?

Dr Trotter: Yes. The UniSpacer implant is an alternative to total and/or partial knee replacement surgery. An affected patient’s knee has either developed chronic degeneration of the inner knee compartment through natural ‘wear and tear’, or the condition may have developed after a knee injury that resulted in a cartilage or meniscal injury. Regardless of whether or not a patient has ever undergone any prior surgery to attempt to address any known prior cartilage problem, the UniSpacer is designed to relieve pain and provide stability due to malfunctioning degenerative or absent cartilage.

The UniSpacer has been currently designed for the (medial) inner side of the knee only as the frequency and degree of medial compartment deterioration far exceeds that of lateral or outer knee compartment cartilage degeneration.

KNEEguru: What is the difference in outcome between a Unispacer procedure and an osteotomy?

Dr Trotter: In my opinion, the outcomes of UniSpacer can be superior to an osteotomy (in the hands of UniSpacer surgeons who are routinely implanting the device) for these reasons:

• Osteotomy procedures (surgical bony realignment) require anatomy altering bone cuts that can sometimes affect future joint replacement procedures.

• Osteotomy typically requires extensive initial postoperative immobilization and decreased weight bearing not involved post UniSpacer.

• Regarding osteotomy, a Dr. Coventry (JBJS 1993) noted that patients who had undergone a high tibial osteotomy and whose body weight exceeded approximately 1.3x ideal had overall poorer results than those that had more ideal body weights. Weight does not appear to be an important factor with the Unispacer.

• Also, Coventry had reported some postoperative motion loss that I have not noted in the current UniSpacer series of patients.

• In some series, a degree of recurrent bowing after a relatively limited number of years has been noted post osteotomy.

Overall, it is difficult to directly compare UniSpacer results with osteotomy. The results of osteotomy are longer term, have been not unreasonable, and have been typically reported in terms of maintenance of the joint realignment. UniSpacer and/or joint replacement series have been reported in terms of scoring scales discussing pre- and post-operative pain relief and functional capabilities.

In the hands of UniSpacer surgeons who are routinely implanting the device where indicated for osteoarthritis, the majority of results have revealed approximately 80-100% pain relief. (These percentages are derived subjectively from UniSpacer patients who are asked about the magnitude and frequency of pain reduction, the increased resolution rate of pain (if it occurs), and from accepted scales of pre-and post-op functional abilities.

KNEEguru: You mentioned ‘unicompartmental’ knee replacement (arthroplasty). What are the differences between a UniSpacer and a unicompartmental?

Dr Trotter: Of the medial, lateral and patello-femoral compartments of the knee, it is widely accepted that the condition of symptomatic osteoarthrosis (‘arthritis’) typically affects the medial (inner) compartment much more frequently and/or with a greater severity than the lateral compartment.

The term Uni-knee has become synonymous with a number of implants or ‘constructs’ (from a number of implant companies) designed to surgically treat the medial (inner) or lateral (outer) compartments of the arthritic knee.  It has also been referred to as a unicompartmental knee implant, as it is only placed in the compartment (typically medial) that is felt to contribute to the overwhelming majority of a patient’s symptoms of arthritic pain and/or instability.

The construct typically involves the insertion of a metallic component on the lower end of the femur that articulates with a plastic (or plastic on metal) component on the upper tibia. These components (in order to be inserted) do require bone cuts/resection, and also fixation with bone cement. The construct is designed to act as a low friction partial knee replacement. If future revision to a bi- or tri-compartmental (total knee replacement) is necessary, removal of the two-piece components and cement are necessary.

More recently, the term Uni-knee has broadened to include the UniSpacer implant. The UniSpacer device, unlike the two-piece construct, is a single component alloy of metallic Cobalt and Chromium, designed for durability and wear characteristics. The UniSpacer does not require significant bone cuts/resection/ligament work or cement fixation, all of which can be inherent in a two-piece metal on plastic unicompartmental construct.

The UniSpacer acts as an interpositional ‘spacer’, in effect taking the place of the worn/degenerated knee cartilage. The early positive clinical outcomes of pain reduction and knee function restoration have been attributed to the redistribution of weight bearing loads and to restored knee stability.

KNEEguru: Are there any contraindications for the procedure?

Dr Trotter: Contraindications against being a candidate would be either if a patient’s outer (lateral) compartment is essentially involved as much (or more severely) than the inner (medial) compartment. The UniSpacer is currently not designed for lateral compartment disease. Also, severe patellofemoral compartment may be a challenge. However it would not necessarily preclude a patient’s candidacy from UniSpacer, as it can be addressed surgically.

FOOTNOTE from Dr Trotter: There have been some cases reported in which second look scopes (rarely needed) have revealed some apparent new cartilage formation (of unknown quality). This is speculative but may account for the perceived improvement of some patients up to one year post-op.

Treatment
Patients with painful knee arthritis have many options to consider prior to surgery. These options include anti-inflammatory medications, cortisone or visco-supplementation (‘liquid-cartilage’) injections, topical solutions, canes and ‘unloader’ knee braces. However, when the preceding conservative treatments begin to fail to relieve a patient’s arthritic pain, surgical options are available. Some surgical options are clearly less invasive than others.

At the Center for Sports Orthopaedics, SC, the Unispacer-‘Uni-knee’ implant has been shown to markedly decrease pain and to restore knee function, alignment and stability. This is achieved by replacing missing cartilage with a single metallic implant. The patient’s own knee is preserved and a patient’s body weight does not appear to be an issue. There is no dramatic bone resection or any metallic/cement fixation required, as a patient’s own ligaments allow for implant and knee stability. The knee is not compromised with regard to possible future complete (or even partial) knee replacement operation(s).

This author has also determined that combining the UniSpacer with proprietary arthroscopic removal of the chronically inflamed deep synovial tissue of the knee further ensures dramatic relief from arthritic pain/swelling. Optimized surgical technique, including post-operative protocols, tends towards correspondingly improved patient results. At the Center for Sports Orthopaedics we have found that early non-braced range of motion and measured implant sizing has led to dramatically optimized results (as compared to the procedure when it was in its infancy).

Post-operative recovery appears to be relatively more rapid than with knee replacement, as the minimally invasive Uni-knee/UniSpacer incision is usually 2-3 inches in length and over the inner aspect of the knee. Non-braced weight bearing as tolerated is typically allowed immediately. A continuous passive motion (CPM) machine is utilized short-term to assist in rapid return of knee motion, as is specifically designed physiotherapy utilized to promote strength and functional motion.

Many of this author’s patients had been followed for 2.5 years (as of Jan. 2005). The results have generally been a very dramatic reduction (or absence) of arthritic pain and improvement in knee function and stability. Many patients have requested and have now received an implant in their other arthritic knee. Although not all are so adventurous, one patient has climbed ‘Diamond Head’ mountain in Hawaii and another is able to engage in yoga.

In Conclusion
Medical and surgical treatment of painful arthritis of the knee has evolved over time. As the population continues to seek out less invasive modern forms of treatment, the utilization of alternatives to knee replacement should increase. The optimized UniSpacer Knee System appears to represent a viable alternative to knee replacement in knee arthritis patients that no longer adequately respond to non-operative measures.