**7.4 Introduction to clinical cases**

146 Modern Arthroscopy

Fig. 14. Flow chart showing the standard protocol for articular cartilage regeneration with

cells, because this is the marker for mesenchymal stem cells.

can be seen, there is no effects of HA on the viability of the PBPC.

CD105+ (106) Based-4ml per vial

Fresh cells are used preferably for the first injection because of a mean viability of 99% compared with frozen cells, which have a mean viability of 87%. It should be noted that 8 mL of PBPC injected into the operated knee has a mean of 20 million CD105+ cells. Historically, the cell marker CD34+ (hematopoietic stem cells) has been used to identify functional cells for bone marrow transplant. We have begun to draw interest in CD105+

Five weekly injections are based on the HA protocol for osteoarthritis, as well as the suggestion from preclinical animal studies involving Bone Marrow Progenitor Cells (BMPC) that an increased number of intraarticular injections is more efficacious (Saw et al, 2009). Table 3 shows the viability of 5 consecutive frozen PBPC samples after mixing with HA. As

**Frozen PBPC from -196ºc Storage Tank**

Viability

A 3.000 2.010 75.10% 3.380 6.050 77.50% B 1.060 10.800 78.90% 0.980 3.750 83.00% C 3.220 16.800 68.20% 2.660 8.230 68.90% D 1.020 5.150 85.10% 0.550 2.370 86.60% E 0.720 7.710 82.20% 0.750 2.780 84.80% **AVERAGE 1.804 8.494 77.90% 1.664 4.636 80.16%** 

Before addition of HA After addition of HA

CD34+ (106) Based-4ml per vial

CD105+ (106) Based-4ml per vial

Viability

PBPC and HA.

Patient

CD34+ (106) Based-4ml per vial

Table 3. Cell count viability.

Five cases are presented here with their respective chondral biopsies and histology. These cases provided explanation to the principles of chondrogenesis in our novel approach.

The patients are part of a larger pilot study in which 180 patients who presented with chondral defects of the knee joint were recruited. Postoperatively, the clinical course of these 5 patients presented an opportunity for a second-look arthroscopy. Two patients underwent contralateral knee surgery, and one patient had removal of a Tomofix plate and screw construct (Synthes, West Chester, PA), providing an opportune setting of anesthesia for second-look arthroscopy. One patient had recurrence of discomfort attributed to a prominent osteophyte and elected for a further arthroscopic procedure. The last patient had returned to football 18 months after articular cartilage repair and sustained a torn anterior cruciate ligament of the previously treated knee. He elected for arthroscopic reconstruction, which provided an opportunity for second-look arthroscopy. Informed consent after discussion of risks and benefits, as well as local ethics committee approval, was obtained before biopsy.
